Something strange is happening with Ben Simmons, who remains one of the most difficult players to properly evaluate in all of the NBA. Well over halfway into a season in which Simmons has cemented himself into the conversation as an elite defender, the Sixers are actually 8.2 points per 100 possessions worse defensively when Simmons is on the floor, per NBA.com. 

This has been the case for most of the season, and the numbers, frankly, are too extreme to take seriously or responsibly dismiss. The 76ers have a 99.0 defensive rating when Simmons is on the bench, which would rank No. 1 in the league by a mile, and a 107.2 rating when he's on the floor. A few weeks ago, I asked Philly coach Brett Brown what he thought of this statistical discrepancy, which has only grown more extreme in the time since. 

"I would put that completely into the weird-stat, I don't care basket," Brown said. "Ben Simmons is an all-league defender. Slice it up any way you want. Just look at what he does, and the versatility with which he does it. Guard a five man. Guard a point guard. Go guard the best player. He's 6-foot-10. He's a stud of an athlete. Just look at the size of him. So that metric you just said -- I've never even heard it, to be honest with you -- but I dismiss it. I aggressively dismiss it."

For a long time, I was right there with Brown. I don't put much stock into advanced stats anyway, particularly the defensive ones, which are hugely dependent on teammates. But then even that logic starts to leak water. Through Tuesday, ESPN's defensive real plus-minus, which theoretically separates an individual defender from the contributions of his teammates, barely has Simmons as a top-200 defender -- 183rd, to be exact, six spots ahead of Carmelo Anthony. 

Obviously, there is no way you could put Anthony and Simmons in a remotely similar defensive category, so it's not a perfect stat. No such thing exists. But when multiple stats say something similar -- not just this season, but last season, too, which we'll get to -- you have to at least open your mind to the possibility of something that seemingly makes no sense. 

So I've been tracking these stats for months. Wanting to dismiss them. Watching hours of Simmons' film. For the most part, there is little empirical evidence that Simmons isn't the defender he's cracked up to be. And yet, if you squint, there's something you can't quite put your finger on that is missing. It's not like watching Draymond Green or Kawhi Leonard or Paul George when they're fully locked in on a mark. There's nothing particularly suffocating, for lack of a better word, about the way Simmons defends. He's always waiting to pounce, but there are a fair number of possessions with no pounce and all wait. 

"He's a free safety at heart," a league scout told CBS Sports. "We tend to think of great defenders as guys who can lock in on one player and shut him down. Ben can do that, we've seen it, but he likes to move around and interrupt different things. I don't know if he's the kind of guy you can just say: 'Go get their best scorer and take him out.' Although nobody can really do that anymore."

If we have even slightly overrated Simmons' defense, we have likely done so on account of, first and foremost, the coverage Joel Embiid supplies. Philly's fully healthy starting lineup, for instance, has a suffocating 97.1 defensive rating over 240 total minutes, per NBA.com. But you take Embiid off the floor, and the defensive rating for all lineups that include Simmons falls to 109.5, per Cleaning the Glass. 

Simmons staggers his bench time with Embiid's, for the most part, so he's playing a lot of his non-Embiid minutes with lineups designed more for offensive spacing and the increased pace Philly employs when Embiid sits. That is certainly a factor in the numbers. But if a guy isn't able to lead a defense on his own, or at least keep it neutral when his sidekick sits, is he really an All-NBA defender?

Also, like Brown said, Simmons gets immediate defensive love, before anyone even cares to look at actual production, just off the eye test. Modern NBA defense is all about length, athleticism and versatility, and Simmons has all these traits in spades. He has as many defensive highlights as any player in the league. Also, if the advanced stats tell one story, the traditional stats say something different. Through Thursday, Simmons leads the league in total steals, deflections and loose balls recovered.

Would it be unfair to brand Simmons' traditional defensive counting stats as empty numbers, similar to the way we've talked for so long about, say, Zach LaVine's scoring, Hassan Whiteside's blocks or Andre Drummond's rebounds? Absolutely. We can examine some strange trends while still recognizing Simmons is a unique defensive menace who, like a great scorer on the offensive end, can beat you many different ways. 

"Not only the athletic ability, but he has great instincts," Al Horford told CBS Sports. "To be a great defender you have to have good instincts and he has them. It comes very natural to him."

To Horford's point about Simmons' instincts, which was echoed by many of the Sixers I spoke with, take a look at the two plays below. What you'll see is something very subtle but very effective. Simmons starts out going over a ball screen, only to stop halfway, cut back under the screen, beat the ball-handler to the downhill spot and force him into a tough shot, then contest that shot with length.

Here he does the same thing to Jimmy Butler:

These are the kind of improvisational maneuvers you can't teach, that a defender just has to feel in a split-second moment. If you go under the screen from the start, the shooter casually pulls up. But by initially appearing to run into the screen or fight over it, the ball-handler, who is acting on his own instincts, is going to continue downhill into what he expects to be open space. Simmons knows this. He's already felt what's happening two steps ahead.

Of course, it's not all instincts. You have to have Simmons' length and quickness to cut under a screen that late and still be able to stay in front of an explosive downhill athlete like Donovan Mitchell or Butler. We love to romanticize athletic intellect, waxing poetic about a quarterback reading the field or LeBron James sixth-sensing his surroundings for a zip pass to the weak-side corner, but in the end you have to have the physical gifts to actually make the play. 

Here Simmons goes over a dribble hand-off like any other defender in the league would. The difference is Simmons has the length to not just contest the shot from behind, but actually block it. 

"His ability to guard smaller guys, bigger guys. He's always engaged and locked in, he's just a beast on the defensive end," Tobias Harris said. 

Here is Simmons, at 6-foot-10, staying with and eventually blocking the shot of 6-foot-1 Darius Garland:

When you hear people talking about making "multiple efforts" defensively, this play below is what they're talking about. The first effort you'll see is Simmons cutting off Jayson Tatum's initial penetration. A lot of players, after they accomplish that much, will relax and stand up. Simmons, on the other hand, stays in a stance and proceeds to fight over the top of a ball screen, which is the second effort. But he's still trailing the play, and again, a lot of defenders, particularly after they've already expended a lot of energy, would be content to just stay behind Tatum and funnel him into another defender. Simmons, instead, makes a third effort, accelerating to get back ahead of Tatum and create a turnover. 

You want to see a whole-package defensive possession? Watch here as Simmons first denies a simple wing-entry pass some 30 feel from the basket when most defenders just concede that pass. Then he gets switched onto Julius Randle, a very strong, bull of a player, but Simmons powers him off his spot and makes him catch the ball further from the basket than he'd like. Then he knocks the ball away from Randle with active hands, interrupting his rhythm, before ultimately stoning Randle with high hands as he tries to bully Simmons to the basket. 

That is, by my count, five efforts on one play. The denial, the switch, the fight for position, the deflection, and finally the one-on-one defense and contest. This is normal stuff for Simmons. 

"His ability to stay on the play for a full possession is honestly something I've never been around," Sixers backup guard Raul Neto told CBS Sports. "Because his length is so great, and he's such a great athlete, it gives him a chance to maybe gamble for steals or deny a pass really hard, and, like, if his man goes backdoor or whatever, he can recover and still contest a shot or create a steal from behind."

An example of what Neto is talking about:

And another from the same game:

 "That's kind of rare, to be honest," Neto continued. "A lot of guys won't keep pursuing the play once they're behind it. But Ben just keeps playing. That part of his defense is amazing."

Horford and Harris both touched on Simmons' ability to "recover" from his mistakes, which speaks to what Neto said about Simmons' ability to stay on plays. He can pursue steals without compromising the team defense is he misses. But that doesn't always work out. 

That's good effort jumping out on Trae Young and trying to create some chaos, but when Young plays it out and Simmons just sort of slaps at the ball from behind, the defense collapses and a shooter is left wide open. 

The following play is a similar breakdown that starts with Simmons losing sight of D'Angelo Russell, who slides into a slight relocation when Simmons turns his head trying to make a steal. This forces Furkan Korkmaz, Philadelphia's corner defender, to rotate up to Russell, leaving Damian Lee, his man, unoccupied. And it is Lee who strolls in unabated for the uncontested board and put back. 

You watch enough film, and there are enough plays like this to at least catch your eye. Simmons floats around trying to cause improvisational chaos and sometimes gets burned. But for the most part, these plays more the exception than the rule. 

The rule is that Simmons is a super-long athlete with first-rate instincts and a super-charged motor that basically allows him to contest anything or anyone from anywhere on the court. What's strange, again, is the numbers don't add up to quite the same conclusion. Simmons, with all this ability, only contests 5.3 shots per game, which ranks 69th among guards, per NBA.com. 

Draymond Green, a similar position-less defender with a do-it-all role, contests over 10 shots a game. The same goes for Pascal Siakam, another similar defender to Simmons. Kawhi Leonard, Marcus Smart and Jaylen Brown, all these versatile guys with similar defensive makeups contest more shots per game than Simmons does. 

Again, these stats aren't perfect. Classifying what is a contested shot and what isn't can be a gray area. Still, it goes back to the initial point: If one stats says something weird, you dismiss it, but when multiple stats say something weird, you kind of have to listen. It isn't just this season, either. Last season, the Philly's defense was also 3.8 points per 100 possessions better when Simmons was on the bench. That's almost 6,500 minutes of evidence that the Sixers are a statistically better defense without Simmons. 

It's crazy. But it's what it is. 

To be fair, this trend flipped last postseason, when rotations tighten and Simmons plays more minutes alongside Embiid. Philadelphia's postseason defensive rating dropped by almost four points per 100 possessions when went to the bench. And again, it's worth re-mentioning the Philadelphia's 97.1 defensive rating with its starting lineup this season. 

You do the math, and some of this can be explained by the particular lineups in which Simmons is deployed. Playing without Embiid hurts his numbers. As part of a great team defense, he only makes things greater. But as his reputation as a likely first-team All-NBA defender has grown beyond reasonable doubt, the simple truth is that nobody else in that conversation carries such extreme negative defensive numbers. 

The Celtics, for instance, are actually better statistically when Marcus Smart goes to the bench, but it's by less than half a point. Anthony Davis, who was once considered the front-runner for Defensive Player of the Year and is a lock for first-team All-Defense, statistically makes the Lakers a worse defense when he's on the court, but again by barely a point. Same for Paul George, who is a clearly elite defender that only swings the Clippers' statistical defensive fortunes by a point. 

You can dismiss these variances. George, in particular, has missed a ton of games, which throws this stat way out of whack. But Simmons has only missed two games, and we're talking about almost eight points per 100 possessions in the wrong direction as part of a trend that dates back more than a season and a half. You can be like Brown and completely ignore these numbers, wave your hand dismissively in the face of nerdy analytics. Or you can think about them, wonder what's going on, try to settle on your own explanation. But whatever you do, you can't act as though they don't exist.