Source: ESPN 2010-1151.36 SEASONSHARE OF REBOUNDSRANK 2013-1452.21 2011-1251.45 2012-1351.85 When Oklahoma City added Paul George and Carmelo Anthony this offseason, there was speculation about whether the two would diminish the brilliance of Russell Westbrook. Three games into the season, Westbrook appears unfazed, already hinting at another triple-double season. However, the George and Anthony moves do seem to have had an effect on another piece of the team’s core identity: For the first time in a decade, the Thunder are struggling to rebound.The Thunder have grabbed just 47.5 percent of available rebounds in their first three games — about 6 percentage points lower than last year and 24th in the league. As a team, the Thunder haven’t finished outside the top 10 since they moved to Oklahoma City. 2016-1753.41 2014-1552.62 2017-1847.5%24 2015-1654.71 2009-1051.76 The Thunder’s rebounding is off this yearRebound rate for Oklahoma City, through Oct. 24, 2017 2008-0950.87 Three games aren’t a lot to go on. There’s all manner of small sample size nonsense around the league that isn’t likely to hold up: Kevin Durant is not going to average four blocks a game, and the Cavaliers won’t field a lineup that is outscored by 100 points per 100 possessions (uh, probably). But with the Thunder’s rebounding, there’s reason to suspect these early struggles on the glass may signal an underlying change in the team.For years the Thunder had more rebounding than it knew what to do with, and rebounding, unlike shooting, carries steep diminishing returns. This made the team’s allocation of skills unusually lopsided, even as it shed a lot of rebounding in the past two offseasons. The summer of 2016 saw the departure of Durant — one of the best rebounding small forwards in the league — as well as Serge Ibaka, who was traded to Orlando, but the Thunder still managed to finish first in rebounding last season.This offseason, Enes Kanter, who is virtually unplayable on the defensive end but one of the best rebounders in the league, went to New York in the trade for Anthony. Domantas Sabonis, whose draft rights were acquired in the Ibaka trade, was a throw-in to the deal for George with Indiana. The trades have forced the Thunder to play almost exclusively small, with Patrick Patterson slowly working his way into the rotation after offseason knee surgery and looking very rough in the minutes he’s seen. The team has undeniably added talent with George and Anthony, but it has also traded big-for-small — and may have weakened its bedrock identity in the process.Through three games, Anthony has more made 3-pointers (7) than he does rebounds (6) as the starting power forward. George has fared better on the glass, but his 8.9 total rebound rate would still be a career low. The proposition was that Anthony and George both rebound well for their positions, and Westbrook is one of the best rebounding guards of all time. But with the small-ball starting lineup being badly outrebounded, it’s an open question just how valuable that out-of-position rebounding really is.Westbrook took a lot of flak a season ago for piling up empty rebounds — “deferred” rebounds, in the nerd parlance — that saw his big men box out so he could collect the board and rip up the court. The NBA hasn’t begun publishing player tracking stats yet this season, so we don’t have a breakdown on how many of Westbrook’s rebounds have been contested, but it’s going to be something to keep an eye on. Rebounding is essentially a team stat, but if Russ can collect 9.3 rebounds per game with a 15.7 rebound rate from the point guard position and his team still doesn’t win out on the glass, it calls the value of those boards into question. Either Westbrook’s rebounds are a little less valuable than we believed or the Thunder’s new-look roster has rebounded so poorly that Westbrook’s outsized contribution doesn’t matter. (Or, you know, it’s one week and three games and we need to settle down.)So far, the rebounding dropoff has cost the Thunder a little more than 4 points per game in second-chance points compared with last season. (They’re at -1.7 in net second-chance points, down from +2.6 in 2016-17.) This is a very noisy way to look at rebounding, but it’s also the most material way. OKC was outrebounded 58-45 against the Timberwolves on Sunday night in a game it ultimately lost on a buzzer-beater. That’s not the sort of game Oklahoma City is accustomed to dropping. But if the Thunder keep boarding like they have early on, they may have to get used to it.Check out our latest NBA predictions.