Al Jefferson has gained a lot of notoriety as a rebounder. He has been in the top eight in the NBA in rebounds per game three times in his career, including last season, when he was also fifth last year in defensive rebound percentage. His career mark in that stat ranks seventh among active players. He has averaged a double-double four times during his career so far, and before this season only once averaged fewer than ten rebounds per 36 minutes.
That all has changed this season, where Al Jefferson is putting up the lowest numbers of his career in the following stats: total, defensive, and offensive rebounds per 36 minutes, offensive rebounding percentage, defensive rebounding percentage, and total rebounding percentage. His rebounds per game (again: offensive, defensive, and total) is at the worst rate he's put up since 2005-06, which was still before he became a regular starter.
So what's going on with Big Al? And how badly (if at all) is it hurting the team? There's a few factors contributing to his decline on the boards, so let's break down a few of them.
Lance Stephenson: Okay, let's get the elephant in the room out of the way: Lance Stephenson is "stealing" rebounds from Al Jefferson. Stealing is in quotes because, despite their drop in rank, the Hornets actually have a higher team defensive rebounding percentage than last year, and because Lance Stephenson hasn't been that strong an offensive rebounding threat. That being said, Stephenson did get a reputation for being selfish with stats — particularly with rebounds — when he was with the Indiana Pacers. So, yes, sharing the court with a guard who ranks seventh in the league in rebounds per game is causing Jefferson's rebounding total to go down. Is this impacting the team all that much, though? In situations like these, I'd typically argue that a perimeter player crashing the boards that hard in full pursuit of a rebound would hurt the team's transition offense, but the Hornets don't regularly run a fast break, and the positioning of the backcourt players has nothing to do with that. Whether or not this aspect of Stephenson's game in particular has caused chemistry issues within the Hornets, I don't know; I'll leave that analysis up to people who actually spend time in the Charlotte locker room.
The defense is worse: Last season, the Hornets' opponents shot 44.2 percent from the field. This year, they're shooting 46.1 percent. On average, this means there are 3.5 fewer defensive rebounding opportunities per game for the Hornets (and, as defensive rebounds are much easier to get than offensive rebounds, this is pretty big). I don't think it's ridiculous to assume that Jefferson could get one more rebound per game if the Hornets had the same caliber defense this season. And, it should be noted this is mostly because opponents are having an easier time getting to the rim this year, a shot which produces more rebounding opportunities for the offense, while taking them away from, say, a post defender who has to contest the shot. This is without a doubt something that has negatively impacted the Hornets, but losing one extra defensive rebound per game is pretty far down the list of the worst consequences of Charlotte's defensive deficiency.
Different personnel and lineups: Last season, the most common lineup that had Al Jefferson playing without Josh McRoberts (who, as you saw, was a pretty versatile forward) featured as his frontcourt partner a rookie Cody Zeller, who had issues playing post defense against larger opposing players. Jefferson spent very, very little time playing with Bismack Biyombo, a very skilled rebounder who adopts a rim protector role on defense, keeping him close to the basket. This year, according to Basketball Reference, Jefferson is playing the most time at the power forward position since the 2009-10 season, when he was 25 years old. This year, his most common frontcourt partners have been Marvin Williams (who has spent the bulk of his career being a more productive rebounder than McRoberts was last season), Cody Zeller (who added muscle over the offseason and can play the glass much better than he could during his rookie season), and Jason Maxiell (who doesn't do much else other than get in the way). It's probably not everything, but it makes a difference. Has this hurt the team? I'm sure most of us wish the team still had the McRoberts of last year, but Zeller improved quite a bit, too. The jury is still out on Marvin Williams. I'd prefer Maxiell stayed on the bench. So the answer is that yes, this doesn't result in anything positive because of the impact it has on Jefferson's numbers, but he's probably not the one who should be found at fault in this case.
Maybe he's just getting older: Al Jefferson's about to turn 30. He's not especially injury prone, but he's nearly seven feet tall, weighs 265 pounds, and has missed time with injuries during five seasons, including the plantar fasciitis rendered him completely ineffective during last season's playoffs. That does take its toll on professional athletes, even ones who seem durable. Maybe Al Jefferson's just getting older, and can't bang on the glass as much as he used to. Is it possible that's not the case? Absolutely. Is it likely that a player past his physical peak on the age curve can't use his athleticism to his advantage as well as he once could? Sure is. And I'm willing to guess that Jefferson's age, as well as the factors listed above, has contributed to his regression in the rebounding department.
Dumb stupid luck: Statistical anomalies happen. Maybe this is one of them.