For Joel Embiid, it always comes back to defense.

He led the NBA with 30.6 points per game. He averaged 26.2 points in the six-game, first-round win over the Toronto Raptors.

But when a concussion and broken eye socket suffered in the first-round finale cost him the first two Eastern Conference semifinal games in Miami, the Sixers missed his defense most.

It’s back.

The Heat shot 47.1% in their two wins. The Sixers held them to 35.1% Friday night in a 99-79 win. It was the second-fewest points the Heat have scored this season, and it was the fewest they’ve scored in their eight playoff games, in which they averaged more than 110 points. They scored 31 fewer than usual, 29% less.

The difference?

Joel Hans Embiid.

With him in the middle, the Sixers aren’t just the better team; they’re the far better team.

He dominated Game 3 as a shell of himself.

He was ragged, and rusty, and exhausted, as you’d expect. He was distracted by a protective facemask, and that was an issue, but for onlookers and opponents it served as a foreboding prop that lent a Phantom of the Opera mystique to his comeback. He was clearly out of condition — lingering concussion symptoms means that he couldn’t work out for a week — but he was active, and strong, and present.

“What I pride myself on is, really, defensively. That’s where my presence is really felt — on the defensive end,” he said. “That’s really one of the reasons why, (by) playing, I thought I could have a huge impact.”

Embiid celebrated his return on social media. He used a line from the Bane character in a Batman movie, “No one cared who I was until I put on the mask,” on Instagram. He tweeted a “We back up!” meme from The Wire.

He was tired, but giddy.

Embiid scored just 18 points, and he grabbed a modest 11 rebounds, but for every second of his 36 minutes the Heat knew he was there. His understudies — DeAndre Jordan, Paul Reed, and Paul Millsap — are shadows of the man who might be named the Most Valuable Player as early as Sunday night. Embiid has become an unstoppable force when the Sixers have the ball, but he’s always been an immovable object when the other team has it.

Bam, Bam

Miami center Bam Adebayo scored 24 points in Game 1, 23 in Game 2, shot 71.4% from the field, and averaged 10.5 rebounds. Against Embiid on Friday, Adebayo was 2-for-9, scored nine points, and had three rebounds.

Embiid returned to lower the boom.

“Bam was dominating,” Embiid said. “I was really pissed off, watching that other big man go play well against my team.”

As ever, Embiid’s play had a trickle-down effect. The Sixers gathered 37 rebounds in Game 1, 34 in Game 2, and 44 on Friday. Power forward Tobias Harris had 10 rebounds in Games 1 and 2 combined. He had 10 on Friday alone.

This is how the Sixers can win in the playoffs. This is how every team that wins in the playoffs wins in the playoffs. Those teams defend with discipline, they rebound with vigor, they run when they can.

The Sixers can do none of that without Embiid. They can win the series with him.

Shoot, they might be able to win it all.

Heroic

The Heat had no mercy.

Embiid not only was coming off a concussion, which makes another more likely, and not only did he have the fractured orbital near the right eye, but he also has a torn thumb ligament in his shooting hand that will require postseason surgery. This was a grown man’s game, and he played it like a grown man.

Adebayo gave Embiid a shot to the jaw and throttled him on the same play in the second half. It was one of the four times Embiid hit the floor.

Every time, the sellout crowd of 21,033 gasped in fear. Every time, he got up. Heart is a metric you can’t measure.

Beyond the Heat’s shooting percentage, their point total, and the loss, you have to appreciate the subtleties of the game to fully appreciate Embiid’s impact Friday. For instance, Embiid helped on Jimmy Butler and Tyler Herro with 5 minutes to play in the first quarter, leading to a missed shot. Soon after, Gabe Vincent pulled up for a jumper (and missed over Embiid) — a jumper that would have been a layup had Embiid not been on the floor. That play led to an early possession layup from James Harden.

With Embiid as insurance behind them, Sixers guards were more willing to challenge Heat perimeter players. How effective was Embiid’s presence?

Point guards Kyle Lowry and Vincent did not score.

“He’s the anchor,” said shooting guard Tyrese Maxey.

“He’s a huge factor, even when he’s not scoring,” said Danny Green, a former all-defensive team selection. “It’s a big difference when he’s guarding Bam.”

Embiid’s return was not assured until minutes before the 7 p.m. scheduled start. Heat coach Eric Spoelstra was asked before the game about Embiid’s possible return:

“We want to take on that kind of challenge.”

Spoelstra was less glib afterward.

“He’s a big impact,” Spoelstra acknowledged, after Embiid had erased his center for 48 minutes. “We’ll just have to figure it out.”

Embiid figured it out long ago. He left Kansas after one season, a raw basketball newcomer with virtually no offensive game but with the athleticism of Bill Russell and Hakeem Olajuwon. Injuries have diminished him for now, but he’s still an agile, 280-pound giant with elite eye-hand coordination, even when those are being protected by a mask.

“It starts on defense,” he said, “and on defense, I don’t really need to see everything.”

That’s clearer than ever.