In losing four of its last five games, preventing offensive rebounds has proven to be a problem for Boston. Opponents haven't even done a particularly good job at turning those rebounds into points, but it's still putting a tremendous stress on the Celtics' defense and allowing points that Boston simply cannot afford to give up with every game proving to be a grind.
The typical reaction is that the bigs are at fault and, for sure, a lack of simply putting a body on opposing frontcourt players has hurt Boston, particularly going up against some active bigs lately. But the Celtics acknowledged after Thursday's loss in Chicago that much of the blame falls on the players on the perimeter for allowing dribble penetration that is leading to breakdowns in help defense.
"One of the things we’ve struggled with all year is dribble penetration," said Rivers. "When it happens, our bigs have got to help -- that’s what they’re trained to do and that’s what they should do. The [drawback] to that is, the next guy has to crack back, and we are not doing that very well. If you’re a big, you’re frustrated because you’re doing your job, and your guy gets the rebound -- that’s frustrating."
Rajon Rondo knows he's partly to blame for those struggles and admitted after Thursday's loss that, "Dribble penetration is killing us."
Let's look at an instance of dribble penetration to show what's happening (CSN Screenshots):
This is from the final moments of the third quarter in Wednesday's loss to the Detroit Pistons. Rodney Stuckey runs a little pick-and-roll on the left wing with big man Greg Monroe and Rondo can't get through it fast enough to prevent Stuckey from penetrating (he makes the decision to gamble for the ball by poking at it from behind, essentially taking himself out of the play from there). Center Greg Stiemsma, who has already rotated to pick up Monroe while JaJuan Johnson recovers from hedging on the pick-and-roll, rotates again to defend Stuckey's drive.
Here's the frustrating part to Rivers. Stiemsma defends Stuckey's layup attempt, but four white shirts are looking at the play instead of rushing to get a body on Monroe, who is just parked in the paint waiting for a rebound opportunity.
Stuckey can't convert the layup because of Stiemsma's help, but Monroe outleaps swingman Mickael Pietrus -- the only player who gets close enough to make a play on the rebound -- for a tip-in that put Detroit out front heading to the fourth quarter. The Pistons only mustered nine second-chance points off 11 offensive rebounds, but when a team shoots 47.3 percent from the field overall, you absolutely cannot allow them to generate four extra buckets off second chances.