We forgot about it because of the scary things LeBron James did in the second half of Game 2 on Sunday, but Miami’s defense was strangely off for much of that win. They lost track of Danny Green on two 3-pointers, errors of miscommunication that resulted in shrugged shoulders, the kind of stuff championship teams leave behind in April. Kawhi Leonard took advantage of lazy or nonexistent boxouts on two offensive rebounds, and he back-cut a ball-watching LeBron late in the first quarter.

It recalled the listless Heat that allowed an offensively challenged Celtics team to ring up Spurs-level scoring numbers through the first five games of last season’s Eastern Conference finals. That team mostly cleaned things up after getting Chris Bosh back. This Heat team cleaned things up in Game 2 with one of the most devastating 15 minutes of basketball the league has ever seen.

Last night, they were awful defensively for the entire game. They can be bad defensively and get away with it against some teams. But this is the NBA Finals, against a brilliant and unselfish San Antonio team, and the Heat will lose just like this if they continue to make very basic NBA mistakes.

That’s why Erik Spoelstra was fuming after the game. He wouldn’t discuss the Spurs’ hot shooting. “I don’t even want our guys to bring up that side” of the game, he told reporters, by which he meant that he didn’t want any talk of how the Spurs might miss some shots in Game 4. “Every shot they wanted to get, they got. We got what we deserved.”

It was jarring to watch. Mike Miller went under a high screen for Gary Neal, allowing Neal’s easiest 3-pointer of the game. Both Miller and James chased Manu Ginobili as he rocketed off consecutive screens from Leonard (who has six arms) and Tim Duncan, leaving Leonard uncovered, a mistake that resulted in a chain reaction of confusion that left Neal open again from deep. Neal made the shot (duh). Miller reacted by shrugging his shoulders as Dwyane Wade, Neal’s original cover, slammed his hands against his legs in flailing frustration.

There was so much more. Miller left Ginobili to double-team Duncan with about 1:20 left in the first half, apparently convinced someone would take Ginobili for him if he got the ball. No one did. Ginobili missed an open 3-pointer, and Green, a hero tonight, slid past a lazy LeBron boxout to nearly tip the ball back in. James and Wade have been terrible boxing out in this series, and it was going to catch up to them at some point. That came with about 7:40 left in the third quarter, when Tony Parker curled off a Duncan screen, caught the ball, and found himself far more open than he’d typically expect with Duncan’s man, Bosh, running out to trap him.

This was a theme all game: Miami’s coverage on Parker was soft. Maybe that was by design. But Parker had breathing room tonight, and he used it to slice through Miami.

The Spurs worked their way on that possession to a wide-open Green 3-pointer, which missed. But Leonard outleapt James for the rebound, in part because James did not even attempt to fight him for it. Ginobili missed a 3-pointer right away, and Leonard ran right around a pseudo boxout by James for another rebound.

There were more possessions like this. The Spurs have rebounded 30.5 percent of their own misses in this series. That would have ranked fourth overall for the season. The Spurs ranked 29th during the year, and they almost take pride in minimizing the importance of crashing the offensive glass. But they’re killing the Heat that way in this series, and though Leonard and Duncan deserve credit for their work and their smarts, the Heat have been disturbingly sloppy. It is strange to see.

A lot of Miami’s defensive breakdowns in this game, and especially the miscommunications, involved Miller. It’s worth noting Shane Battier logged nearly 900 more minutes than Miller this season. Spolestra said at shootaround earlier Tuesday that he had Miller in his back pocket as a possible wild card as early as the Chicago series. Battier, to his credit, said he was happy for Miller. “He’s been a true pro,” Battier said, “and he’s seizing the opportunity.” He also noted that he was losing some of his power forward minutes to LeBron, which is kind of true, since LeBron has to guard power forwards without Battier to take that ugly job. “Last I checked, LeBron has a slight basketball advantage over me,” Battier quipped. “If this were Jenga, I’d be kicking his ass.” I wonder if Spoelstra, looking for solidity on defense, might reinstate Battier in Game 4.

I also wonder if it would even work, given Battier’s cold shooting and how generally beat-up he looks. He’s never had a full season like this, guarding big men so the Heat could play smaller without having LeBron defend power forwards. Battier named Zach Randolph and David West as the two toughest physical challenges among the league’s power forwards, and he said guarding those types all season reminded him of his sophomore year in high school. Battier was a small-ish center then, and among his head-to-head assignments were Jon Jansen and David Bowens — both of whom went on to careers as linemen in the NFL. “I was a 200-pound center,” Battier remembered, “and they were beating the hell out of me.”

And oh, hey, LeBron did not look like himself. He attempted zero foul shots in a game for just the 10th time in his career, and the first since 2009. He was strangely passive for much of the game, settling for jumpers and looking unnerved — to the point that on one third-quarter possession, with San Antonio treating him as if he were Rajon Rondo on the pick-and-roll, James took a step inside the 3-point arc to splash a 20-footer. James is smart. He knows that’s a bad play. He did it anyway, and he looked uncomfortable through the “Should I do it?” process.

The passivity was strange in part because LeBron had a beastly two-minute stretch of post-ups in the first quarter — a bullying jump hook over Leonard, a drawn foul, and then a back-down of Green that led to a Chris Andersen dunk. The circumstances were favorable for some of that “aggressive LeBron” stretch. Leonard sat for part of it, and James is clearly more comfortable posting Green. And both Miller and Ray Allen were in the game, giving Miami maximum spacing around LeBron on the block. But it’s not as if LeBron doesn’t know how to do this under imperfect circumstances, or even through the very aggressive help San Antonio was sending.

Spoelstra knows this, too. LeBron post-ups have been among his go-to after-timeout plays, and he went there again with 4:50 left in the third quarter and the game slipping away. LeBron caught the ball one-on-one against Leonard, turned to face the basket, and saw Ginobili playing far off Wade. This has also been a theme all series, and Wade in the first half found ways to punish the Spurs for this calculated disrespect by cutting off the ball while his defender’s eyes were elsewhere. Wade, as was the case in Game 2, could not carry that over into the second half. He needs to ditch all jumpers and floaters that come with 10 or more seconds left on the shot clock. They aren’t going in.

The Spurs are making James see bodies. And as fantastic as he is, LeBron can become a passive player when good defenses throw those bodies at him and the ball stops moving. This is what happened during his meltdown two years ago against Dallas — the Mavs blocked his path in every direction, and the Heat offense, in its infant stage then, just bogged down. LeBron didn’t know what to do.

He didn’t have to jack a jumper on this possession; he could have driven to his left, or backed Leonard down on the block. But Leonard has played James well, with quick feet, giant arms, and a quiet tenacity. He has earned James’s respect, and the bit of caution that comes with that. So have the Spurs. James has to be better than he was tonight, though.

The Heat this season tried to short-circuit this bad habit by creating a whirring offensive system with constant movement, rapid-fire passing, unpredictable screening, and ace long-range shooting. That offense doesn’t exist anymore on a full-time basis. Playing three of the league’s top six defenses will do that; great defenses are great because they take away your best stuff.

But there are other factors at work. Wade is hobbled, unable to make all the cuts, passes, and finishes that keep the system flowing. Bosh hasn’t been himself since tweaking his ankle midway through the Indiana series. And though Miller has shot well in effectively replacing Battier, he doesn’t offer quite the same level of solid screening — an important ingredient in a lot of Miami’s best stuff, even if the Battier screens are just decoys.

More notes from a strange game:

• The Spurs’ coyote mascot is as terrifying in person as he is on television, with his cracked-out, bloodshot green eyes and his general lack of pants. He wears jersey no. 2! That is not a misprint.

• San Antonio fans are a sensitive bunch, prone to some lighthearted (and occasionally darkhearted) martyrdom, so let me be clear: That opening diatribe about Miami’s poor defense in no way discredits San Antonio. It takes a good team to exploit Miami’s poor defense. On the missed 3-pointer that kicked off the sequence of offensive rebounds highlighted above, Green came open at the end of a splendid Parker-to-Duncan-to-Ginobili-to-Green series of passes, all executed almost immediately upon the catch, which only two or three teams could even think of pulling. And Duncan made things even dicier for Miami’s scrambling defense by pump-faking a pass to Green before throwing a no-look dish to Ginobili.

Another one: Tiago Splitter’s dunk near the end of the first half, via a pick-and-roll with Ginobili, looked in real time like a horrid Miami breakdown. But rewatch the thing, and you’ll see Ginobili had a hand in that breakdown by looking off Splitter and duping the entire Heat defense into thinking he was about to pass elsewhere.

The Spurs are just so damn skilled.

• Matt Bonner left the postgame scene early, sandwich in hand. He’d be happy to know the Spurs’ media team decided to use his empty locker as a staging ground for Parker’s French-language postgame media session, just to separate the giant crowd of reporters waiting at Parker’s locker.

• One commercial break entertainment consisted of two fans tossing giant foam french fries into giant french fry containers.

• It has been fascinating how little we’ve seen LeBron on Parker, and how badly the Spurs have won that battle when Miami has gone that route. They got two straight easy baskets in Game 2 when LeBron shifted to Parker, and tonight, Spoelstra gave the matchup about 80 seconds before abandoning it. That came midway through the second quarter, when Spoelstra used a lineup that included neither of his point guards and had James guard Parker. The Spurs immediately went to a side Parker/Duncan pick-and-roll that netted an easy bucket for Duncan. Less than a minute later, LeBron missed a 3-pointer the Spurs happily gave him, and LeBron’s man (Leonard) ran out behind the entire Miami defense. LeBron didn’t think much of Leonard’s run-out, since Spoelstra had temporarily assigned him to Parker, but nobody else picked up Leonard in the confusion. Leonard dunked on the break, and Spoelstra called timeout — his 163rd timeout of the game, I think. That was it for LeBron-Parker, and for those non–point guard lineups.

• Two fans held up giant cutouts of The Internship’s Vince Vaughn and Owen Wilson, which seems a weird thing to do at an NBA game.

• Leonard had a couple of steals in this game that made you leap from your seat if you enjoy defense. On one Mario Chalmers/LeBron pick-and-roll, he slid off of LeBron and onto Chalmers, poked away Chalmers’s dribble with his left hand, and gathered it with his right. Another came on the first Miami possession of the second half, when the Heat tried to set a tone by going to James on the block. Leonard jumped the play and swiped the entry pass.

• Here’s a bad number: Wade is 6-of-21 in the playoffs on post-up shots and has drawn exactly zero shooting fouls on his post-up possessions, per Synergy Sports. The real Wade shoots between 45 and 50 percent on post-ups and draws bundles of fouls. The Heat didn’t even try him down there tonight. The Heat in Game 2 called a Wade post-up for their first play of the second half, and he could barely float the ball over Green’s hand. The lift just isn’t there.

• Wade’s also 9-of-29 on isolations, which loosely translates to “STOP DOING THIS.”

• Sometimes sports are just really cool. Here’s Green, cut by both the Cavaliers and the Spurs before finally latching on in San Antonio, speaking from the postgame podium: “I’ve watched hundreds of these. I never thought I’d be up here.”

• Wade said something interesting about LeBron’s shot selection, after assuring one inquisitive questioner that LeBron was not, in fact, sick. He said the Spurs’ strategy of sagging far off of both him and LeBron almost tempted them into taking jumpers, even though both know they should stay in attack mode. “It takes away your aggressiveness,” Wade said, since open jumpers are shots “you can make in your sleep.” James shot 40 percent on 3-pointers this season and 46 percent on long 2-point jumpers — a Nowitzkian number. He should have graduated past this, but, again, credit the Spurs for making him think hard about driving.

Let’s see what happens in Game 4.