Celtics’ offense thrived against Heat’s zone through Al Horford

The Heat trailed 17-4 after a flurry of Celtics transition plays led by Jayson Tatum. Erik Spoelstra responded by shifting Miami’s defense into a 2-3 zone.

If it wasn’t for Kelly Olynyk landing a pass in the fourth row on their final chance to come back, the change would’ve been the greatest gift the Heat gave Boston all night.

The analysts on NBATV quickly acknowledged that there may not be a better player to man the high post against the zone than Al Horford. Horford ended the night with his second career triple-double — after his wife urged him to finish the deal. The other came against Michael Carter-Williams’ 76ers in 2018 — my shameless Syracuse Orange reference in a 2-3 zone article.

Brad Stevens utilized the zone in spots in the past. The Brooklyn Nets used it liberally against the Celtics to great effect earlier in the year. Overall, its prevalence is up in the league this year. Brooklyn and Miami lead the way, with nearly 10 percent of their defensive possessions in the zone.

Miami did not run it well. Its initial implementation helped the Celtics reach nearly 50 percent from three-point range and maintain a 20-point lead. They tried it again early in the third quarter, but difficulties emerged when James Johnson and Olynyk shared the court at the same time sent Olynyk to the top of the zone.

That forced Olynyk to check Horford. Miami probably assumed he would pass before attacking against the zone. Instead, he managed to do both, dropping 19 points and 10 assists.

Horford overloaded the top of the zone. With only two defenders there, Horford could draw up the back line into the high post, or pull in the defenders from the top of the zone to free up a pair of shooters situated on the wing. Marcus Smart’s 4-of-8 night from three played a big role in breaking the zone, as did nine threes between Jayson Tatum and Kyrie Irving.

Miami managed to rush Horford into a back-door pass that Semi Ojeleye couldn’t handle to begin the second. However, Stevens continued to trust Horford to run sets, and immediately he caught Hassan Whiteside sleeping in transition and slashed through an unset Miami zone for a dunk through a foul.

Two plays later, Horford set himself in the high post again, pulling the back line toward him and freeing Ojeleye for a reverse layup on the same exact setup. Miami failed from the jump on many possessions, facing too many shooters and passers on the perimeter to guard Boston. Here, defenders targeted Terry Rozier and Horford, totally ignoring Marcus Morris.

Horford did everything necessary against the zone, this time getting a touch inside to pull Derrick Jones Jr. miles from his zone on the left wing. As much as the Celtics have played make-or-miss basketball and leaning on the three, they executed beautifully to find open space on Monday.

Miami’s decision to go zone, and stay zone, forced the Celtics toward a level of ball movement they’ll need in the postseason. Horford kept rolling after a six-assist first half. With Miami pulling within 11, he swung the defense hard to the right with a difficult pass and forced an overplay on Smart. It wasn’t exactly the Syracuse 2-3 zone, even with Dion Waiters playing in it.

Boston’s success showcased the possibilities of running offensive sets through Horford. Beyond breaking down the zone, he pushed the ball in transition with a beautiful pass to Gordon Hayward, set Irving up off the ball and posted up to generate his own offense. His presence on the court of late has made or broken Boston’s offense.

The Celtics may not see the zone once in the postseason. Spoelstra still gave them the perfect playoff tune-up, getting back to Boston basketball where the ball practically moves itself.