For the past week or so, the Miami Heat have been playing all kinds of defenses. They sprinkled in man-to-man, switching, drop, and a bunch of different zones. And now, they were going up against the Boston Celtics.

Not only do the Celtics have the best offense in the league by a pretty good margin(4.9 points better than the second-best offense Denver Nuggets, per Cleaning the Glass), they are on track to having the best offense ever.

It was going to be interesting to see how they plan for that type of offense. The last time they met, the Heat had a 117.0 defensive rating, and that was bad. In this game, the Heat’s defensive rating was 135.1! and had a 69.5% effective field goal.

A lot of the damage was done in transition. Per InStat, they allowed 2.07 points per possession in transition. It’s hard to have a good defense when you’re getting demolished on the break.

In the half-court setting, the Heat went primarily zone defense with some sprinkles of man-to-man(M2M).

Heat’s Man vs. Zone splits were on trend tonight once again:

Celtics Half-Court PPP
vs. Man: 1.54 (24 possessions)
vs. Zone: 1.12 (63 possessions)

But when Horford was on the floor Boston scored 1.31 ppp vs. zone, vs. 0.76 with him off, which carries over from last year.

— Couper Moorhead (@CoupNBA) December 1, 2022

The numbers say the zone was much better than M2M, even when you consider the 1.31 PPP with Al Horford on. And although that’s the case, I don’t think M2M was as big of an issue as the stats show. The results were clearly bad, the process was there.

So, let’s go through some of those defensive possessions.

They started the game in the zone and immediately gave up a clean dunk to Jayson Tatum. The ball is getting swung from one end to the other, which results in three defenders around Marcus Smart.

He makes a good read to Horford in the corner, Tyler Herro rotates and forced him baseline. That drive forces Kyle Lowry to rotate, and Bam Adebayo sinks down to take away the dump-off pass to Derrick White. The issue here was Tatum having a clear lane to cut. Caleb Martin has his back turned and Max Strus is paying attention to the ball. That should have been one of them stopping that cut.

For the next possession, they decided to go M2M with their usual switching:

There’s a Horford-White pick-and-roll(PnR), which ends up being a switch with Lowry on Horford in the post. He does a great job fronting the post and Martin is active to discourage the post-entry pass. The ball gets moved and Tatum drains a 3.

They continued with M2M for the next few possessions:

All three possessions resulted in a bucket, but the first clip is exactly what you want — a tough leaning mid-range from Jaylen Brown against Adebayo.

The next two clips were dumb errors that resulted in Adebayo getting back cut because he was ball-watching and Martin not being engaged. It didn’t seem that they were exploiting some glaring weakness exclusive to M2M.

Nevertheless, they threw in some zone next. That’s been the theme of the game where they just flipped through M2M and zone a lot.

Both possessions resulted in Tatum getting a clean look from 3. These were the shots that the Celtics wanted. They didn’t have to work for any of those shots, as they were taken with 18 seconds left on the shot clock. And it’s these types of looks that they were getting consistently.

But the biggest problem for both zone and M2M was their perimeter defense. It was no wonder that both types of defenses were getting cooked and giving up good looks.

When they were going M2M, no one could stay in front. It was blow-by after blow-by. The Celtics also were using their flare screens perfectly.

You can see at the 10-second mark, White is setting a flare screen for Tatum against Haywood Highsmith, who’s already helping off at the nail. With Highsmith that deep at the nail, he wasn’t going to recover back to Tatum, who was already going downhill. That meant Duncan Robinson had to switch and you probably already know how that’s going to turn out.

This wasn’t just a M2M problem. Their perimeter defense got exploited even in the zone:

It’s as if anyone was able to penetrate the defense, get both feet inside the paint, force the defense to collapse, and if the rotations aren’t perfect, that will result in open 3s. In all those possessions, big gaps in the zone allowed anyone to dribble through.

If they were able to hold them off from penetrating the defense, the Celtics countered that by having multiple guys that can flash to the middle and make the defense react:

That’s what makes the Celtics so dangerous. They have multiple players that can penetrate the defense off the dribble and multiple guys that can flash to the middle to collapse the defense, and make a quick read for an open 3.

The Celtics had 35 open 3s — they attempted 45 in total.

When it comes to dealing with the flash, that opens up other potential looks:

In the first clip, no one is there to take away the flash or meet Tatum earlier, and because of that, he can go in for a floater. In the second clip, the Heat adjusted by having Lowry step in early to the shot away. His presence discouraged the pass inside but opened up a skip pass to Grant Williams in the corner.

You’re in a pick-your-poison situation.

Finally, there were still plenty of good zone possessions, but that mainly was without Horford or with one of Brown or Tatum:

The rotations here were on point. Everyone was moving quickly and early. They didn’t allow any gaps in the zone to allow dribble penetrations. They did everything right.

That’s the thing about that zone against the Celtics. Everything has to be right. There’s little margin of error and it’s difficult to take all of that away constantly. Zone can and has been effective, but not to this extent — not at this volume.