The Miami Heat have a tight grip on their second round playoff series against the Brooklyn Nets. The Heat have a pair of double-digit victories, and the Nets have yet to break 90 points.

After Game 1, much was made of the Nets attempting a season-low 12 shots in the restricted area (making half). Brooklyn did a better job getting into the paint in Game 2, but once it got there, the Heat were waiting. The Heat defended 20 of the Nets’ 28 shots at the basket Thursday night, according to NBA.com’s SportVU Player Tracking Box Score. Of the shots the Heat contested, the Nets made just four (The SportVU system defines shots defended at the rim as ones when the defender was within 5 feet of both the rim and the shooter).

The Heat have tightened their defense in the playoffs. During the regular season, they ranked 10th and 13th, respectively, in opponent shot attempts in the restricted area and opponent field-goal percentage in the restricted area. And they were frequently accused of saving energy for the playoffs. Although we can’t directly measure energy expended, the results would seem to indicate that the Heat have shifted into their playoff gear.

The Heat’s defenders are connected by taut strings — one player moves and pulls another into a different position. To make the system work, a team needs mobile big men who can blitz a pick-and-roll and challenge a shot at the rim, often on the same possession. It’s become increasingly obvious over the past three seasons that Chris Bosh has grown into an ideal cog for this system.

Bosh isn’t considered a devastating rim defender; he ranked just 28th in the league in blocks per game this season, behind suspect defenders such as Terrence Jones, Al Jefferson and DeMarcus Cousins. But blocks only capture a small portion of rim defense. On Thursday night against the Nets, Bosh defended nine shots at the rim, of which the Nets made just one. In these playoffs, Bosh has been defending an average 7.5 opponent shots per game at the rim, allowing opponents to shoot just 42.4 percent on those shots. Of players who have defended at least 40 opponent shots at the rim in these playoffs, only Tim Duncan, Roy Hibbert and David West have allowed a lower field-goal percentage.

Bosh may not block a ton of shots, but he gets in the way. In the Heat’s system, that’s enough to give them one of the most destructive defenses in the league.