Hakuho and fellow sumo wrestlers train. Tim Foley Snatch Hakuho from his peak, shove him into your DeLorean and send him into any point in the past — including the 1790s — and he will almost certainly be a favorite to stay in the ring, on his feet, against any human or human-like god-giant that he runs into. We know this.But considering his unprecedented domination of his competition, his broad skill set and, yes, even his controversial willingness to push boundaries in pursuit of victory, he can likely match any sumotori legend for legend as well. The shikiri (pre-match ritual) takes several minutes. The wrestlers clap to attract the attention of the gods, lift their hands to show they are unarmed, stomp the ground to scare away demons and throw salt in the ring to purify it. They repeatedly crouch as if about to start the match and then stand up after a few moments of glaring at each other. When they are finally ready, they creep toward their starting stance.There is no bell. The match starts with a tachi-ai (initial charge), which generally happens the instant the opponents are set.Harumafuji lunged from his crouch, low, exploding toward Hakuho in an effort to take control of the bout early. Instead, he caught a quick palm to the face — and then air. His momentum carried him clear out of the other side of the ring, like he’d tried to bull-rush a ghost.The match had lasted one second.Kisenosato scowled and walked out of the ring area. Commentators didn’t quite know what to say; one of the English announcers let out a long “hmmmmm.” The crowd booed its champion.This is not normally how a match of this scale plays out. Side-stepping an opponent’s charge is legal but considered beneath the dignity of top sumotori. The move is known derisively as a henka (変化), which translates to “change” or “changing,” while connoting the root “strange” (変). That it would be used by an all-time great in one of the most consequential matches of his career was strange indeed.With all Hakuho has accomplished, his greatness is unquestionable, but his legacy is an enigma. It is already beyond being measured by wins and losses, or even by yusho (tournament wins) or sansho (special prizes), so incidents like this now take on particular importance. But judging him by heel turns would be reductive. The best way to measure Hakuho’s legacy is to pit it against legend.Enter thunder and lightning. The final match of the 2016 Haru Basho — one of six professional sumo tournaments held each year — was a day-15 championship-deciding showdown between the sport’s top yokozuna.1Yokozuna, 横綱 (literal: “horizontal rope”), means “grand champion.” Named after the decorative rope that yokozuna wear during their ring-entering ceremony. Officially recognized as the highest rank in 1909. Hakuho, the White Peng,2Hakuho (白鵬) translates literally to “White Peng.” Peng is a mythological Chinese bird described in Zhuangzi as being so large that “his wings are like clouds draped across the heavens.” the dominant force in sumo over the past decade, was 13-1 in the tournament and hadn’t lost since his opening match.If he could beat rival Harumafuji — himself a winner of seven Grand Tournament championships — Hakuho would win a record 36th Emperor’s Cup, about the equivalent of a 24th major in tennis or golf.3Since 1926, the winner of each honbasho (official tournament) has received the Emperor’s Cup. There have been six honbasho per year since 1958. If he lost, he would have to wrestle again (almost immediately) in a tiebreaker against 13-2 ozeki4Ozeki, 大関 (literal: “great barrier”), means “champion” and is presently the highest rank besides yokozuna. (Before 1909, yokozona was a ceremonial title and ozeki was the highest rank.) Kisenosato, who was waiting ringside. Tegata are collectible autographs featuring a wrestler’s name and handprint. The one on the left is allegedly Raiden’s; on the right is Hakuho’s. These are not necessarily to scale. Raiden’s hands are said to have been 9.4 inches from palm to tip. Fish scales of greatnessThere is perhaps no more intricate ritual among sports fans than debating the relative merits of greats across eras.Over time, athletes get stronger, faster and better-trained, and benefit from accumulated institutional knowledge. NFL kickers, for example, have been getting better at a nearly constant rate for 80-plus years. So we have meta-debates about whether athletes should get more credit for dominating the competition in an earlier, top-heavy era or for excelling in a mature sport with a broader talent pool. For example, who’s the more impressive outlier, Dan Marino or Peyton Manning?If we want to imagine athletes from different times competing, do we assume they would have enjoyed all the advantages and disadvantages of the comparison era, or do we focus on strict time-traveling scenarios? And, crucially, in time-traveling scenarios, are you bringing present-day athletes into the past, or are you snatching past legends and bringing them to the present?From what we know about his career, Raiden won more often than Hakuho on a bout-by-bout basis. Yet though Raiden’s career was longer in years, it was short on matches. Here’s every Makuuchi division sumo career for comparison: Raiden, on the other hand, was well above average in height, weight and BMI. At 6-foot-6, he was just about 6 inches taller than his typical opponent, and his 373-pound weight gave him an 80-pound advantage. But there’s an important factor here: Relatively speaking, Raiden isn’t that much bigger than Hakuho. Raiden was about an inch and a half taller and 25 to 35 pounds heavier. Hakuho, by virtue of being less massive than many opponents, is especially strong and/or skilled for his size. In other words, because of the size difference across eras, Hakuho has the advantages of a smaller, more agile fighter without the disadvantage of being that much smaller than Raiden.Note that this is a minor variation from the standard “people get better over time” argument, because it applies relative to their era. It’s not only that Hakuho has been as dominant as he has been in a likely tougher era, but also that his dominance is a product of qualities (strength/speed/skill) that also would be likely to advantage him against Raiden. Tournaments grew in size, length and quantity throughout the 1900s, and in 1958, sumo adopted the current structure of six grand tournaments per year (one every two months), with 15 matches each. Both Raiden and Hakuho are clearly the top wrestlers in their given eras, but how good are they relative to how good we expect top wrestlers in their eras to be?For this chart, I’ve plotted historical win percentages for wrestlers ranked ozeki or higher, with the number of years they competed at those ranks represented by bubble sizes: Raiden’s career — like Hakuho’s — didn’t pass without controversy. It’s said that on account of Raiden’s dominance, some of his favored techniques were at least temporarily banned from the sport. And for reasons that appear to be lost to history, he was never awarded the title yokozuna. The Yokozuna Stone at the Tomioka Hachiman Shrine — home of the first professional sumo tournament — has the names of every yokozuna inscribed on it, plus one: the “peerless rikishi”6Rikishi, 力士 (literal: “powerful man”), means professional sumo wrestler. Raiden.This is the burden of Hakuho’s dominance: He is no longer competing with his peers; he’s competing with the peerless. The highest-ranked sumo wrestlers like Hakuho wear the yokozuna rope during dohyo-iri (the ring-entering ceremony). Tim Foley Hakuho — born Monkhbatyn Davaajargal and given the shikona Hakuho Sho — is the son of a six-time Mongolian wrestling champion and Olympic silver medalist in freestyle wrestling. Despite his pedigree, Hakuho was an undersized sumo prospect — weighing only 137 pounds when he started training at age 15 — and almost went unrecruited. Although he would eventually reach 6-foot-4 and competes at around 330-340 pounds today, he is lighter and thinner than the majority of his opponents. Taller, heavier wrestlers win (a little) more often — hence sumo wrestlers tend to be, well, big. But the relationship between size and success isn’t nearly as strong as you might think, and it gets weaker if you control for division and era.7In a regression to win percentage per tournament using height and body mass index (we use BMI instead of weight because height and weight are highly correlated) as variables, the r-squared produced is around .05 (meaning, roughly, that about 5 percent of the variance in tournament results can be explained by the height and weight of each wrestler alone), which, again, weakens as you control for division and era. However, the sample sizes are large enough to pick up meaningful trends.For this chart, I’ve compared the relative importance of height and weight for predicting top-division wrestlers’ win-loss rate in a given tournament. Values above 2 are roughly “significant” for a given five-year period.8I ran regressions for each year over a rolling five-year period and recorded the t-value (strength of stat divided by standard error) for “height” and “BMI.” Also, each bubble is colored to show how many “wins above replacement ozeki” (WAROZ) each wrestler would be expected to win over the course of their career, based on their win percentage relative to their era and projecting as if they’d wrestled 90 bouts per year as healthy wrestlers do today. By this metric, Hakuho leads all with 182 WAROZ (and counting), with second-place going to Tachiyama (who had 115 wins and eight ties in 128 bouts between 1909 and 1918) at 175. Raiden finishes eighth with 143 WAROZ.Here we can see that top ozeki winning a huge percentage of their matches seems to have been almost expected hundreds of years ago. This is consistent with a number of things we know about sumo tournaments back then: With less focus on “winning,” they were a bit more like exhibitions. And we know that opponents were sometimes literally picked out of the crowd.11This is how Raiden’s mentor, Tanikaze, got his start. Hakuho, however, competes in an environment in which losses for top-level wrestlers are considerably more common than they were in Raiden’s time, but he has maintained an extremely high win percentage nonetheless.Behold the henkaYokozuna face a lot of pressure to retire the instant they start to decline. It’s considered dishonorable to hold the rank of yokozuna and not be among the best in the sport.12When a maegashira (the fifth-highest rank in sumo) beats a yokozuna, it is called a kinboshi (“gold star”) and earns the maegashira a special bonus payment — which they receive every tournament for the rest of their career. So a yokozuna sticking around past their prime is literally costly to the sumo association. So although we’ve made the argument that Hakuho might have an advantage over Raiden in both prowess and résumé, recent events raise a third, more fraught point of comparison: legacy.After Hakuho’s win by henka at the Haru basho, Mark Buckton of The Japan Times — a former amateur sumo wrestler who has covered professional sumo for 18 years — called for the White Peng’s exit. Addressing Hakuho directly, he writes:At its lowest ebb, following the hazing death of Tokitaizan and former yokozuna Asashoryu feigning injury the only yokozuna worth his salt in both performances on the dohyo and behavior off it was yourself.True, you are still the best there is in a mawashi.And that is how you should be remembered.Not as a man who resorts to a final day henka against a fellow yokozuna, on his way to yusho No. 36.Go now and you go in true Japanese fashion, falling on your sword for that Day 15 performance so unworthy of your name.In a phone interview, Buckton said that he thought Hakuho’s henka was disgraceful and that he was confident most Japanese sumo fans felt the same way. He said he believes the move was akin to an act of desperation — Hakuho sees his skills slipping and is resorting to dirty tactics in a last-ditch effort to stay on top of a sport that isn’t merely competitive exhibition but has its roots as a martial art in Shinto.That’s fair enough. But for cold-blooded empiricists obsessed with win-maximization, this may all seem strange. If henka aren’t banned, not using them is just bad game theory, right?Unfortunately, henka are hard to analyze with data. They aren’t considered a winning move themselves, and only winning moves are recorded. Hakuho’s win was scored as a tsukiotoshi (“thrust down”). What even constitutes a henka is not clear-cut — particularly in instances in which they fail.However, what little evidence we have suggests that they work. Lon Howard of Sumo Fan Magazine attempted to crowd-source some henka data by having readers nominate matches that contained possible henka and then asking the readership to vote on whether they actually were. Overall, the possible henka led to victory 63 percent of the time; among a subset of moves that voters were certain were henka,13Attempts with agreement and 10 or more votes. that figure rises to 92 percent.Although that data isn’t conclusive, it makes sense. If you’re playing rock-paper-scissors and your opponent does nothing but throw rock for 250 years, throwing paper may be very effective.Stigma-based policing of the sport’s standards is defensible. Normalizing the henka might fundamentally change the sport’s dynamics too much, but outlawing it may create a havoc of gray areas. But such a defense should anticipate that sternly discouraging the move may not prevent its selective employment by a wily rikishi with a New England Patriots-style commitment to winning.In a tear-soaked post-match interview, Hakuho appeared to express regret for the tournament ending the way it did. But he did not clarify his side-step’s strategic underpinnings, such as whether it was planned, or a response to something he saw while the wrestlers were getting set, or a reflexive reaction to Harumafuji’s charge itself.But regardless of premeditation, consider the story told on the faces of the competitors: A quarter-millennium of Sumo evolutionHakuho vs. Raiden isn’t a story of a sport that has stayed the same for hundreds of years, allowing us to make clean, crisp comparisons between the two champions. But it isn’t a story of a sport changing every couple of years either.Although there have been significant structural changes — like the setting of tournaments at 15 matches long, the introduction of tiebreakers, and the treatment of yokozuna as an official rather than ceremonial rank — the sport is always fundamentally about knocking the other guy down or getting him to step out of the ring first. Many trends happen over decades or centuries, caused by whims of history that can be hard to pick up in a data set.But some simple metrics — like wrestler height and weight — can tell a pretty interesting story. And to understand how Raiden and Hakuho match up with each other, it helps to understand how they compare physically to their eras. Raiden Tameemon. Explore 250 years of sumo data Hakuho trains in 2014. See more: A History Of Sumo, an interactive graphic by FiveThirtyEight showing centuries of sumo wrestlers, and The Sea of Crises, a 2014 Grantland article on sumo and Japanese culture.CORRECTION (May 13, 5:30 p.m.): An earlier version of this article included a photograph that was incorrectly described as portraying Hakuho. It has been replaced with the correct photo. Hakuho and Harumafuji one second after the start of their bout in March. Kyodo The growing international talent poolIf a hypothetical tale of the tape across a couple of centuries is a little too abstract for you, consider that the dramatic shift in the balance of power in sumo’s demographics that has been taking place of late also has implications for our matchup.Before 1972, no non-Japanese wrestler had ever won a basho. The first was Takamiyama, a Hawaiian sekiwake (the third rank, behind yokozuna and ozeki) who otherwise had a relatively undistinguished career as a sumotori. But he then founded the Azumazeki stable — one of the regimented groups of wrestlers who live and train together and to which all active rikishi belong. There he recruited and trained Chad Rowan — a former high school basketball all-star from Hawaii — who took the shikona Akebono, became the first non-Japanese yokozuna and won 11 Emperor’s Cups.Today, international wrestlers have taken over the sport. In January 2016, then-31-year-old Japanese ozeki Kotoshogiku won his first tournament. This might have been an unremarkable event, except that it was the first tournament won by any Japanese wrestler since January of 2006. Of the 58 tournaments in between, 56 were won by Mongolians; the other two were won by a Bulgarian (Kotooshu) and an Estonian (Baruto).Here’s how this has played out since 1970: Note that Japan’s share of champions will improve by at least a tick in 2016, while Mongolia’s will decline, after the country’s three-year stretch of winning all the tournaments.Mongolia has had all this success with only a small fraction of the sport’s wrestlers — around a quarter of those in the top (Makuuchi) division and less than 5 percent of those who compete overall. This likely is because the Nihon Sumo Kyokai (the sport’s governing body) limits each stable to one non-Japanese wrestler, so the standards for foreign prospects are extremely high.This carries some likely implications:Most obviously, the non-Japanese pool of sumo talent is likely growing faster than the number of slots for non-Japanese talent. This probably advantages Hakuho’s strength of competition in our matchup because it implies that he could be the best of a much bigger talent pool than sumo wrestlers of the past. It also implies that while the non-Japanese wrestlers make the talent pool stronger than it was, limited roster slots for them keep it weaker than it could be.On the other hand, the sumo talent from Japan may be declining. Sumo requires major physical (putting on weight) and time (years of non-stop training) commitments. Sumotori lead rigid and structured lifestyles year-round, the potential for fame and fortune isn’t that great, and Japan has an advanced economy that may afford better opportunities to athletic Japanese youth.But even a relatively weak Japan today could be stronger than a relatively strong Japan more than 200 years ago. The population of Japan is now about five times the size of what it was when Raiden was active, making the pool of potential sumotori that much richer.10Moreover, the talent pool back then may have been even smaller relative to today’s than the population numbers suggest, as the vast majority of sumo wrestlers used to come from just the Hokkaido prefecture. This painting of sumo wrestlers by Utagawa Kuniteru II, shown in full on the lower right, is from 1867. In the closeup views at left and top right, Raiden, who is without a yokozuna rope, is pictured among several of the top-ranked wrestlers. The basic style and structure of banzuke have gone unchanged for hundreds of years. The one on the left, from 1796, lists Raiden as the top-ranked ozeki in the West division. On the right is a banzuke from 2012 that lists Hakuho as the top-ranked yokozuna in the East. The average height of sumo wrestlers appears to have declined between the mid-1700s and late 1800s but has been rising fairly steadily since.9Yes, according to the data, there was a wrestler in the late 1700s who was (allegedly) 7-foot-4. He was an ozeki named Shakagatake and had several (winning) appearances in the 1770s before dying at age 26. There is art depicting him as a giant.In the latter half of the 20th century, this upward trend has been aided by the arrival of non-Japanese wrestlers, who have tended to be tall. Note the non-red dots on the charts; they tend to be well above the overall trend.For BMI, we see a similar rise for all rikishi, but with a clear divergence between the tall and heavy Americans and the tall but relatively slender Mongolians.The American (green) wrestlers, all from Hawaii and of Pacific island ancestry, have tended to be huge — both tall and hefty for their height — and had a pretty good run for a while between 1989 and 2002. Konishiki won a few tournaments and then yokozuna Akebono and Musashimaru solidly contended for top honors (becoming the first two non-Japanese yokozuna in the process).But the Mongolians — who have had four yokozuna — tend to be less hefty than their Japanese counterparts, defying the trend of the past 50 years.Compared with the other top-level sumo wrestlers who have been active during his career, Hakuho, at 6 foot 4, is about 3 inches taller than average, but his top tournament weight (in our data) of 340 pounds is 5 pounds lighter than average (putting his BMI well below par). Before Hakuho (born in 1985), before Taiho (born in 1940), before Hitachiyama (born in 1874), before Jinmaku (born in 1829), before the United States of America (born in 1776), there was Raiden.A legend of Japan’s Edo period, Raiden set a standard for greatness in the sport that would last hundreds of years. With centuries separating the two legends’ careers, Raiden vs. Hakuho may be one of the most time-bending sports comparisons imaginable.Fortunately, we have data.The visual history of sumoAs far back as the 18th century, a banzuke listing each wrestler’s rank in the hierarchy of professional sumo has been made before each honbasho (official tournament), often with elaborate detail. Some have visual guides to the various wrestlers and act as a kind of program to the events; others resemble intricate box scores. These collectibles have preserved vital information about which wrestlers were involved in each tournament, including their shikona (ring names), ranks (seedings) and hometowns.Banzuke are the backbone of sumo stats-keeping; other information such as tournament and match results that are gathered from historical newspapers or books all tie back to them. Alexander Nitschke (a German sports data nerd) has a website called Sumo Reference where he has combined banzuke information with other sources of tournament data — including by hand-parsing thousands of lower-division match results for years — to make the most comprehensive sumo data set on the internet. It includes tournament results for most contestants going back to 1761 and individual match results for bouts back to mid-1909. He has let us use that database for this article.Below is a chart that outlines the entire recorded history of Makuuchi division (top-level) professional sumo, from the 1761 Fuyu (winter) Basho through the now-infamous 2016 Haru (spring) Basho. Before around 1900, height and weight had a fairly tenuous relationship with winning. It has gotten stronger in the past century, but size advantages have never been much of a guarantee of success. For a modern example: In the 1980s and 90s, Konishiki — an ozeki who topped 600 pounds — often faced off against Wakanohana, a future yokozuna who was an inch or so shorter and more than 300 pounds lighter. Konishiki went 2-8 against him.Sumo styles can broadly be broken down into two types: Oshi-sumo, or “thrusting” style, and Yotsu-sumo, or “grappling” style. The former is about brute force and pushing your opponent out of the ring; the latter is more about forcing your opponent to the ground or using their momentum against them.As one might expect because of their sizes, Raiden preferred the Oshi-sumo style, and Hakuho the Yotsu. The trade-off for height and weight is pretty basic: Being big makes a wrestler harder to move, but less agile; being small can make it easier for a wrestler to maneuver but leaves him vulnerable.In the 20th century, there appears to have been a period in which larger-than-average wrestlers were more successful than they had been in the past (or are today), at a time in which the average wrestler was growing larger than ever.In this chart, I’ve plotted the height and BMI for each of the top-division wrestlers for each tournament, colored by country of origin: Hakuho has won 36 grand tournaments, more than any other professional sumo wrestler in history. TIM FOLEY Although the discipline of sumo wrestling may have existed in various forms for well over a millennium, it isn’t the sport stuck in time that it is sometimes made out to be. It has experienced controversy throughout its history. In the 17th century, the unseemly practice of samurai wrestling each other for money was banned, only to be brought back with official sanction and standardized rules.The first known professional tournament was held in 1684, and the first sumo organizations began issuing written rankings in the mid-1700s — just in time to document the rise of sumo’s most legendary figure.Raiden was born Seki Tarokichi in 1767 — about 100 years before the Edo period ended — and competed under the shikona of Raiden Tameemon. Raiden is a combination of “thunder” (雷) and “lightning” (電) and translates roughly to “thunderbolt.” Mentored by the first non-posthumous yokozuna, Tanikaze, Raiden was a legend trained by a legend. He went undefeated in 24 out of the 35 tournaments he entered, and despite a much shorter tournament structure that had no method for breaking ties, Raiden finished with the most wins outright in 17 tournaments and tied for the most wins in 11 more. As there were no official tournament winners until 1909, none of these are considered official “yusho” or tournament wins, but no one would top 28 tournaments (officially or unofficially) for more than 150 years.The Thunderbolt was an absolute monster among men — 6-foot-6 and 373 pounds — large enough to physically overpower opponents of the day. His top-division win-loss record of 254-10 (96 percent) is easily the best in recorded sumo history.5If you adjust for draws, which have essentially vanished from the sport these days, Raiden’s effective win percentage drops to 93. But the gap between him and his closest competition grows, with no other wrestlers reaching 90 percent. Hakuho has won 85 percent of his upper-division matches, leading modern-era wrestlers.