Celtics focus on boxing out as defensive rebounding lags in preseason

The Boston Celtics cruised to a 138-107 victory over the Cleveland Cavaliers at TD Garden on Sunday night, but coach Joe Mazzulla used the blowout to spotlight a pressing concern: defensive rebounding. With his full roster available for the first time this preseason, Mazzulla started Chris Boucher at center in a small-ball look, watched Anfernee Simons lead the second unit with 21 points, and repeatedly removed players who failed to box out as he tried to set a standard before the regular season.

Simons scored a game-high 21 points, hitting six 3-pointers, while Josh Minott added 16 off the bench and Derrick White contributed 16 points, seven rebounds and five assists. Boston shot better than 52 percent from the field and knocked down 40 percent of its 3-point attempts in an offensive display that rarely faltered against a Cleveland squad that did not bring its usual starters.

The victory masked a recurring weakness. The Cavaliers collected 21 offensive rebounds, and while Boston finished with 39 defensive rebounds, the Celtics have surrendered a high rate of second-chance opportunities across three preseason games. Through those contests they rank near the bottom of the league...