“Our defense isn’t where we want it to be—yet,” insisted Heat coach Erik Spoelstra, just days after his team surrendered 117 points to the Nets, then the losers of seven straight, and 124 points to the Knicks, who are the Knicks, in consecutive losses. It was a breakdown weeks in the making. The perfume of Miami’s impressive start to the season had concealed a souring defense. Great efforts in coverage had wilted into merely good efforts, and then deficient ones. Errors escalated and compounded, until a team of capable defensive talent made a habit of playing beneath itself.

Spoelstra understood this, which is why he framed the Heat’s season, rhetorically speaking, by its persistence. “That’s the operative word,” he said. “Yet.” On that very day, Miami had used its practice time to drill down on its defense, an effort to more closely align what could be with what would be. “Today was just about solutions, working on some things, watching some film, and pushing our group to get to a different level,” Spoelstra explained.

That was seven weeks ago. Somehow, the Heat defense has only deteriorated further in the time since, culminating in a dismal February that became Miami’s worst defensive month of the season. None of this makes much sense. Jimmy Butler and Bam Adebayo, the All-Stars who lead the team in nightly minutes, are first-class defenders. In terms of tactics, Spoelstra might be the top defensive coach in the game. Yet since December 1—a sample of three months and 42 games—the Heat rank 22nd in defensive rating, just below a Warriors team a few degrees separated from the G League. With the Sixers ailing, last month would have been a perfect opportunity for the Heat to claim the inside track on the fourth seed in the East. Instead, Miami has lost seven of its past 11, allowing one of the most dominant home teams in the league to inch closer to home-court advantage.

The Fall of the Heat Defense Month Defensive Rating Ranking Month Defensive Rating Ranking October 99.3 7th November 105 8th December 111.1 22nd January 111.4 15th February 113.7 21st

This is a portrait of vulnerability. With no stops to fall back on, the Heat lost to the Cavs, Hawks, and Timberwolves, despite leading in the fourth quarter in each of those games. Any run of missed jumpers can now put Miami at risk; the most humbling proof came when Minnesota, without Karl-Anthony Towns, stole a game with a 17-3 run in the final three and a half minutes. Butler and Adebayo were on the floor for that meltdown, alongside new additions Andre Iguodala and Jae Crowder—strong defenders in their own right. Even the most theoretically reliable Heat lineups now regularly bleed points, if not from lapses in effort, then because of the sort of miscommunication that makes it impossible for a scheme to coagulate:

If you catch a random Heat game, you’ll likely clock a handful of exceptional plays made by their opponents. It’s easy to write off those sequences as part of life in the NBA; sometimes a guard as talented as D’Angelo Russell will just drill a quick pull-up 3, no matter the coverage against him. Watch a string of Heat games in succession, however, and those seemingly exceptional plays form a pattern. You may notice that rookie starter Kendrick Nunn seems to get hung up on screens in a way that can throw an entire possession into disarray. You’ll see that Crowder, who just joined the team at the trade deadline, sometimes seems to be playing a looser style of coverage than everyone else on the floor—to the point that his interest in a passing lane causes him to lose track of his assignment. You’ll note just how many teams have begun to target Duncan Robinson, running him through screen after screen until he breaks:

The Heat use a fairly conservative base defense with variations depending on the personnel involved. For example, Spoelstra has preferred to have his bigs drop back to wall off the paint when defending the pick-and-roll, but has given Adebayo, specifically, more freedom to switch when a matchup requires it. Butler or Iguodala might do the same on a screen away from the ball, depending on the other defenders involved. Robinson plays by a different set of rules. It’s his job in the play above to show out on the screen to stall the action before scrambling back to his man. Unfortunately for the Heat, this style of defense leaves them somewhat vulnerable to repetitive processes. Once Robinson’s man (Joe Harris) sets an initial screen, all he has to do is flip it to force Robinson, who is already in over his head, to cover twice the ground.

Of course, this is but one part of the problem for Miami. Even when the Heat take Robinson off the floor, they struggle to contain the ball in the way their scheme requires. When guards and wings fail to stay attached to their assignments, they force Adebayo out of position, leaving the lane exposed. If Adebayo isn’t positioned just so, the Heat might then have to over-rotate to compensate. Any lapse can feed directly into a chain reaction. This is most difficult to manage when a stretch 5 is involved, forcing Adebayo to defend two players at once who could be 15 feet apart:

Adebayo was so concerned about closing out to Kristaps Porzingis that he never quite slid into the path of Luka Doncic. This pulled Butler in from the wing and gave Maxi Kleber, a 38 percent shooter from long range, enough time to knit a sweater before putting up a 3. The entire point of a defensive system is to prioritize certain threats while conceding others. Of late, the Heat have taken some of those concessions too lightly. Dropping back in coverage ups the degree of difficulty when it comes to contesting pull-up jumpers, but that doesn’t mean Seth Curry should pop off for 37 points on 13-of-15 shooting. Miami runs more zone defense than any other team in the league, according to Synergy Sports, but still must extend out to shooters and force them to make tough calls on the fly. A great defensive team will thwart the premise of how it should lose. Yet when the Heat attempt that sort of defiance, their intentions have a way of getting tangled. Someone switches when they shouldn’t, or commits to help too early, or springs a trap that leaves the weak side exposed. With all of the competing, conditional rules governing how the defense works—switch this but not that, zone now but not then, show here but not there—Miami could be the victim of its own elastic ambition.

When that kind of adaptive defense clicks, it looks like the Raptors in the 2019 playoffs. When it doesn’t, it looks like this:

Miami overcame that particular miscue to scrape out a win over the Nets on Saturday, and survived a deluge from Curry and Porzingis to beat the Mavs on Friday. Two thin victories don’t materially change the fact that the Heat defense is in the danger zone. What will happen if Miami’s offense cools off even the slightest bit? How will the team respond if frustrations start to boil over? So far, the Heat have known only the pleasure of Good Vibes Jimmy Butler; what if he begins to see in his Miami teammates whatever irritating qualities he found in Chicago, Minnesota, and Philadelphia? If nothing else, the Heat have clearly articulated the argument against their own title contention. This is a smart, deep, and well-balanced team that has played some of the worst fourth-quarter defense in the league. Miami has been so underwhelming on the road that it can’t run the risk of a first-round series without home-court advantage, and yet it might play itself into just that position.

The Heat defense should be better than this. And yet ...

The operative word is a verdict in itself.