There are two aspects to rim protection. There’s contesting the shots that are taken near the basket, and there’s preventing those shots from being taken.

Both aspects are equally important. The Philadelphia 76ers are in the middle of the pack in regard to both, ranking 18th in opponent field goal percentage in the restricted area (64.4%) and 17th in the percentage of their opponents shots that have come in the restricted area (33%). But when it comes to protecting the rim, there are two different Sixers: The Sixers with Joel Embiid on the floor and the Sixers with Embiid off the floor.

With Embiid off the floor, 36% of their opponents’ shots have come in the restricted area, and their opponents have shot 66.3% there. With Embiid on the floor, those numbers are just 28% and 61.3%.

According to Second Spectrum tracking data, Embiid doesn’t rank very high among high-volume rim protectors, with opponents having shot 60.1% at the rim when he’s been there. That number for two-time defending Defensive Player of the Year Rudy Gobert is just 50.4%.

But the prevention aspect of rim protection is where Embiid really shines when you compare his team’s numbers with him on the floor (28% of opponent shots in the restricted area) vs. with him off the floor (36%). For Gobert, that differential is just 29% (Gobert on the floor) vs. 30% (Gobert off the floor).

The rim protector who’s come closest to Embiid’s on-court impact (in regard to prevention) is Dwight Howard. Lakers opponents have taken 29% of their shots in the restricted area with Howard on the floor, and have taken 36% of their shots there with him off the floor. But those opponents have shot much better in the restricted area with Howard on the floor (65.7%) than they have with him on the floor (58.0%).

When you combine Embiid’s impact in regard to both preventing and defending shots, Philly opponents have averaged 10.2 fewer points per 48 minutes in the restricted area with him on the floor than they have with him off the floor. That’s the biggest differential among 329 players who have played at least 500 minutes for a single team.

Kristaps Porzingis and Larry Nance Jr. are the only other bigs in the top 10, though the Suns’ Aron Baynes (-6.1) is 11th on the list. Other bigs with a differential of at least five points per 48 minutes are P.J. Tucker (-5.9), Dewayne Dedmon (-5.8 in his time with Sacramento), Mitchell Robinson (-5.7) and Hassan Whiteside (-5.4).

Given Embiid’s size and skills on defense, the Sixers do their best to keep him near the basket as much as possible. To break down how that works, we’ll look at some film from one of Philly’s best wins of the season, their Feb. 11 victory over the LA Clippers, in which the Clips scored just 26 points in the restricted area, 10 fewer than their season average. Only 12 of those 26 came in Embiid’s 28:10 on the floor.

Parked in the Paint

Less than 10 seconds into the game, we see how Embiid is going to be guarding Clippers center Ivica Zubac. Really, he’s not going to be guarding him:

If Zubac has the ball, Embiid is free to hang out in the paint. When Zubac doesn’t have the ball, Embiid must be “actively guarding” (within arm’s reach of) somebody or he’ll be subject to a Defensive Three-Second count.

Remaining in the paint allows Embiid to prevent the other Clippers from getting to the basket:

Play 1. Ben Simmons gambles and takes himself out of the play when the ball is swung to Kawhi Leonard on the left wing, but Embiid is there to prevent a Leonard drive and allow Simmons to recover. Then, with Josh Richardson trailing Paul George around a double-screen on the right side, Embiid is there to keep George out of the paint. Richardson is able to get back in front, block George’s shot, and then force another mid-range attempt on a late-clock isolation.

Number to know: Richardson (0.7), Matisse Thybulle (0.7) and Simmons (0.6) are all in the top 16 among guards in blocks per game.

Play 2. Leonard inbounds the ball and then gets a back-screen from Lou Williams. Though his man has the ball 23 feet from the basket, Embiid helps keep Leonard from getting to post-up position on the other side of the floor. The result is another late-clock iso where Marcus Morris misses a tough shot over Al Horford.

Number to know: The Sixers rank third in clutch defense, having allowed just 96.8 points per 100 possessions with the score within five points in the last five minutes.

Embiid sagging off Zubac to protect the paint allows the Sixers’ perimeter players to “top-lock” the guys they’re defending and make it difficult for the opponent to cleanly run its pin-down screens, cross-screens and dribble hand-offs.

Here’s Josh Richardson top-locking as Zubac looks to set a cross-screen for George. Embiid is in the paint, calling out the action and ready to cover for Richardson should George cut back-door:

Shoot Over the Drop

In the two plays in the video above, the guy Embiid was guarding wasn’t involved in the primary action. More often (and because of the way he sits back in the paint), the primary action involves Embiid’s man setting a screen. And on ball screens, Embiid is a classic “drop” defender, sitting back in the paint to protect the basket and encourage the ball-handler to take an inefficient mid-range or non-restricted-area paint shot.

Play 1. Zubac sets an early screen for George toward the middle of the floor. Furkan Korkmaz trails George around the screen and Embiid forces a foul-line jumper that’s off the mark.

Number to know: According to Synergy play-type tracking, 23.4% of Sixers’ opponent possessions, the league’s highest opponent rate, have been pick-and-roll ball-handler possessions.

Play 2. Sagging off Zubac, Embiid again helps Simmons keep Leonard from establishing post position at the left block. Morris eventually gets a ball-screen from Zubac and, with Embiid’s hands down at his sides, is able to step into a comfortable elbow jumper.

Number to know: The 0.86 points per possession the Sixers have allowed on ball-handler possessions ranks 10th.

Play 3. This is the play from the image above, where Richardson is top-locking George to prevent him from curling off Zubac’s cross-screen. He continues to deny George and we get a late Leonard/Zubac pick-and-roll where Simmons gets caught in the screen and Leonard misses a long, pull-up shot.

Number to know: 15.6% of Philly opponents’ shots, the league’s third highest opponent rate, have come from mid-range (between the paint and the 3-point line). Leonard shot 26-for-43 (60.5%) from mid-range in last year’s conference semifinals.

Play 4. Richardson switches a hand-off from George to Morris, who backs out and gets another ball-screen from Zubac. This time, he snakes toward another jumper from the right elbow, but Embiid gets his hand up to prevent it from coming in rhythm. Morris resets and misses a fadeaway. There’s a subtle but important difference between disengaged drop coverage with the big defender’s hands down at his sides (hello Alex Len) and engaged drop coverage with the big having active hands and feet.

Number to know: The Sixers are one of four teams – the Celtics, Clippers and Bucks are the others – that rank in the top 10 in both opponent field goal percentage on shots from between the restricted area and the 3-point line (39.3%, ninth) and the highest percentage of their opponents’ shots that have come from between the restricted area and the 3-point line (33%, third).

Fending for Themselves

Embiid hanging out in the paint puts a lot of pressure on the Sixers’ perimeter players in regard to navigating screens that Embiid’s man sets. This is not the Houston Rockets’ defense, where there’s always another defender to switch the screen. It’s on the target of the screen to get around it and get back in the play.

Play 1. This is the first play of the game and the exact same set as the first play in the first video above. When George comes off that double-screen on the right side of the floor, Richardson gets bumped off the play by Zubac and there’s nobody there to contest George’s catch-and-shoot 3-pointer. When the Clippers ran it again the next time down the floor (in the first video), Richardson had a cleaner path around the screens, George curled tighter off the second one, and Embiid met him at the elbow.

Number to know: The Sixers have been at their best, both offensively and defensively, in the first quarter, outscoring their opponents by 10.0 points per 100 possessions in the opening 12 minutes. They’ve outscored their opponents by 175 total points in the first quarter and have been outscored by 31 points thereafter.

Play 2. Tobias Harris is able to get over the initial hand-off from Zubac to Morris. But then they run another one on the left side of the floor and Zubac sets an additional screen that Harris has to deal with by himself because Embiid is 10 feet away. Morris is able to rise for a pull-up 3-pointer.

Number to know: Because they don’t allow a lot of 3-point attempts, the Sixers’ record hasn’t depended much on how well their opponents have shot from beyond the arc. Teams are just 9-9 (the Clippers were 1-1) when they’ve shot 40% or better from 3-point range against Philly.

Play 3. Shooters make the best screeners and the Clippers set things up by having Landry Shamet set a back-screen for Leonard to get to the right block. Embiid is there to deal with Leonard while Simmons gets around the screen, but then Thybulle doesn’t have any help as Shamet immediately curls around a screen from Zubac. Thybulle is able to chase Shamet off the 3-point line, but he’s able to get to a pull-up jumper inside the right elbow.

Number to know: The Sixers have had the 10th best defense (110.4 points allowed per 100 possessions in 23 games) against the league’s top-10 offenses. That breaks down to 100.0 points allowed per 100 possessions in 10 home games (in which they went 8-2) and 118.5 in 13 road games (in which they went 2-11) against that group. The worst offensive games of the season for both the Celtics (93 points on 103 possessions) and Lakers (91 on 101) were in Philadelphia. The Nuggets, Heat and Jazz all had their third worst offensive games of the season in Philly.

Play 4. With Glenn Robinson top-locking in the left corner, Shamet takes the inside path around a double-pin-down screen from the Clippers’ two bigs. With Embiid sagging in the paint, Zubac then flips the second screen for Shamet to step into a pull-up 3-pointer.

Number to know: The Sixers have allowed 9.4 fewer points per 100 possessions at home (102.7, second best) than they have on the road (112.1, 20th). That’s the league’s biggest home-road differential in defensive efficiency.

Play 5. George gets a hand-off from Williams and a ball-screen from Zubac. Richardson dips his lead shoulder (a Paul George technique, actually) to get around the Zubac screen and contest the shot.

Number to know: The home-road difference has been about the same in Embiid’s minutes on the floor (97.3 vs. 106.6 points allowed per 100 possessions) as it has been in his minutes off the floor (104.1 vs. 113.1).

Embiid hanging in the paint makes life tougher for the Sixers’ perimeter players. But the group is very good at getting around those screens and getting back into the play. Size matters on that end of the floor and when your point guard is 6-foot-10, he can get around a screen and still block a shot.

Not the Same

Al Horford was brought in to help the Sixers when Embiid rests. Philly was, amazingly, outscored by 109 points in 99 minutes with Embiid off the floor in their conference semifinals series against Toronto last year. That stat remains incomprehensible.

The Sixers have been better with Embiid off the floor this season (plus-0.3 points per 100 possessions) than they were last regular season (minus-3.5 per 100). But there’s been an even bigger difference in how well they’ve defended with him on the floor vs. how well they’ve defended with him off the floor.

Horford has been an elite defender in this league. It was just two years ago when he did a terrific job keeping both Embiid and Giannis Antetokounmpo in check in the playoffs. When he’s at the five, he generally plays the same drop scheme as Embiid. But he’s not as big or, at 33 years old (he turned 34 in June), as quick.

Play 1. Montrezl Harrell quickly rolls out of an early screen for George on the left side of the floor. Horford is above the foul line and Harrell is able to get behind him for a layup.

Number to know: The Sixers have seen the league’s third biggest drop in pace, averaging 99.4 possessions per 48 minutes (19th), down from 102.6 (eighth) last season.

Play 2. When Korkmaz doesn’t stop the ball on a “pistol” action (Shamet setting a screen for Williams along the left sideline) and Richardson is trailing Williams’ drive, Horford is seemingly in position to help on the baseline. But he doesn’t stop Williams either.

Number to know: Though they rank sixth defensively overall, the Sixers rank in the top 10 in only one of the “four factors” on defense. They rank third in defensive rebounding percentage, but are 12th in opponent effective field goal percentage, 26th in opponent free throw rate, and 18th in opponent turnover percentage.

Play 3. As Williams brings the ball up the right side of the floor, Richardson is top-locking against George. So George pushes Richardson into a screen for Williams. Stationed at the nail (the middle of the foul line), Horford sees what’s happening, but isn’t able to get to the rim in time.

Number to know: With Simmons playing less than five minutes and Embiid missing five of their 10 games, the Sixers allowed 9.6 more points per 100 possessions after the All-Star break (115.7, 25th) than they did before it (106.1, fourth). That was the league’s biggest post-break jump in defensive efficiency.

The Biggest Impact

Embiid himself is not a perfect defender. In this same game, the Williams/Harrell pick-and-roll produced two layups (one, two) for the Clippers’ back-up center. And Embiid isn’t great at avoiding fouls. His 4.1 fouls per 36 minutes are the 21st most among 228 players who have played at least 1,000 minutes, and he got caught a couple of times – reaching in against George, taking a bad angle against Leonard – in his drop coverage against the Clips.

But when he’s engaged, he’s a force on that end of the floor. Late in the fourth quarter, he showed off his mobility, smothering a Morris isolation to help the Sixers seal the win.

He doesn’t venture outside the paint often, though. When the Sixers have played the Bucks, Embiid has primarily defended Antetokounmpo, instead of Brook Lopez, the more prolific 3-point shooter. And he’s treated the reigning MVP much like a non-shooting center…

Parking Embiid in the paint has been the way to go for the Sixers, who have allowed 8.0 fewer points per 100 possessions with Embiid on the floor (101.4) than they have with him off the floor (109.4). That’s the league’s second biggest on-off-court differential among full-time starters in regard to defensive efficiency. The biggest (8.5 per 100) belongs to Paul Millsap, whose differential is more about how Denver opponents have shot from outside the paint.

So you’d have a difficult time arguing that Embiid isn’t the most impactful defender in the NBA. Having the big man behind them has allowed the Sixers’ guards and forwards to be more aggressive on the perimeter. While the switch-everything Rockets are trying to keep the ball in front of them, the Sixers are happy to funnel it toward their seven-footer.

With the top-locking and chasing over screens, Philly opponents have taken only 33.8% of their shots, the league’s lowest rate, from 3-point range. The Sixers are the only team that has allowed fewer than two corner 3-pointers per game.

Overall, the Sixers have had a somewhat disappointing season. But with Simmons, Embiid and a talented supporting cast, they still have a very high ceiling. They have wins over 10 of the other 12 teams with winning records (they’re 0-3 against Houston and Dallas) and they’re one of two teams – the Celtics are the other – with double-digit wins over both the Bucks (with Antetokounmpo in the lineup) and Lakers (with LeBron James in the lineup).

We don’t know what’s going to happen when the season resumes. But we can be confident that getting to the basket will be difficult when Joel Embiid is stationed in the paint.

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John Schuhmann is a senior stats analyst for NBA.com. You can e-mail him here, find his archive here and follow him on Twitter.

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