Why it’s time to start worrying about the Celtics rebounding again

Bob DeChiara/USA TODAY Sports

Even back in October, Brad Stevens wasn’t quite sure what to expect from his team’s rebounding this season.

“The defensive rebounding has been pretty good,” Stevens said after watching his team during the first week of training camp. “I don't know if that's because we are not rebounding as well offensively, because now we are all of a sudden a great defensive rebounding team. That's the beautiful part about intrasquad scrimmages -- something is going well, you know? I can't tell yet (with the rebounding) but I think our long wings help.”

On paper, the Celtics didn’t do a ton to address the defensive rebounding shortfall that had plagued this team throughout the last three seasons (three straight finishes in bottom five of the NBA in defensive rebounding rate). Aron Baynes was a nice upgrade at center over Amir Johnson on the glass, Daniel Theis had solid rebounding numbers in Europe, Jayson Tatum was above-average on the glass in college, but there were no other meaningful upgrades in this area on the roster. Danny Ainge has always emphasized all-around players over bigs that were strictly rebounders and Stevens always has had to make the best of that handicap on the glass.

Somehow, over the first 18 games of the regular season, this new-look Celtics roster turned into one of the best rebounding teams in the league. In the midst of the team’s 16-game winning streak, they ranked No. 1 in defensive rebounding rate (82 percent) and No. 2 in total rebounding rate. Al Horford was rebounding like he was 25 again (21.4% DRR). Jaylen Brown and Terry Rozier were grabbing boards at a closer rate to an average power forward rather than a guard. The true centers (Baynes, Theis) were holding things down in the middle. It was a well-oiled machine on a nightly basis.

However, since that 16-game winning streak ended on Nov. 23, things have slowly been falling apart on the rebounding front. Over the past 19 games, the Celtics have posted the second-worst defensive rebounding rate in the entire league, grabbing just 75 percent of all available defensive rebounds. That’s a number on par with their bottom-five defensive rebounding rate last year. Theis and Baynes have remained steady with their numbers on the glass, but the rest of the roster has seen notable dropoffs in their rebounding rates (Horford and Brown chief among them).

The sharp regression was on display during Monday’s Christmas night loss to the Wizards as Washington piled up 14 second-chance points off 10 offensive rebounds in the second half. Things got so bad that the Celtics couldn’t even manage to grab a defensive rebound during the final 6:56 of the contest as the visitors manage to score, grab an offensive rebound or turn the ball over during each possession of a 21-8 run to end the game.

So how the hell did the Celtics come up empty on the defensive glass for nearly seven minutes?

“The wing rebounding on the offensive glass,” Brad Stevens said after the game. “I mean, those are killer possessions when you have a stop and you just can’t finish that stop. You know, we turned and looked instead of blocked out most of the night, and it ended up costing us.”

So who were the biggest culprits on Monday night? Let’s turn to the film to find out.