Trying To Make Sense Of This Bizarre Celtics Season Through The Numbers

Brian Babineau. Getty Images.

As I mentioned in the blog this morning, the Celts stink out loud this season. It's maddening, frustrating, embarrassing, annoying, you could pick about a billion adjectives to describe this weird season. There's the reality that they've had the most games out of any team in the league impacted by covid/injuries, but also the reality that even when they have their normal rotation guys available the team has not played up to their potential. Both can be true. 

You could certainly just sum it up to "The Celtics suck" and be done with it, but that's never how my brain has worked. For the last 6 years I've been blogging about this team for this fine website I've always wanted to look into the actual data to see why certain things might be happening, both good and bad. In such a weird season like what we're living through with largely the same roster, I was curious to see what the numbers tell us. It's actually pretty surprising. What this is intended to do is just provide some additional context around what we are seeing while also remembering to factor in the games missed due to injury/covid etc. You'll see it's not as simple as "The Celtics just suck".

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Let's begin.

Offense - Drives

What I was curious about with all this stuff is how this year's team compares to the 2019-20 version that we saw win 48 games and be top 5 on both ends of the floor. Coming off the 11-47 performance from three last night, I know a lot of us were frustrated because it felt like the Celts were settling and weren't nearly aggressive enough at attacking the rim. That's why I wanted to start with just that. How this team and its best players are performing when it comes to drives.

Maybe you are someone who feels like the Jays/Kemba are getting a brutal whistle this season on their drives. Let's start with Tatum. In looking at "driving" data, Tatum (12.3 per) gets to the line about 1.8 times. That's basically the same as Paul George. Here are some other notable guys 

Kyrie (11.9 drives/ 1.2 FTA) 

Simmons (11.6/ 1.6) 

Hayward (11.4/ 1.9) 

The only real outliers are Zion (11.8 /3.1) and Giannis (11.7/3.0)

So while it may feel like Tatum is getting boned, his FTA on drives is basically around everyone else that drives to the rim just as often. That certainly surprised me. 

Then we move to Jaylen. He's at 10.8 drives and 1.3 FTA. Here's how he compares to guys with similar attempts

Curry: 10.3/1.4 

Randle: 10.8/1.2 

Tobias: 10.2/1.2 

Lowry: 10.7/1.2 

Kemba: 10.1/1.2

Again, this surprised me. Unless you think that all of these players are getting a bad whistle, that doesn't really explain it. So why do things feel different? Well, you have to turn to 2019-20. Last year, here were the numbers of all three 

Kemba: 10.9 drives / 1.6 FTA 

Tatum: 10.8 / 2.2 

Jaylen: 8.5 / 1.3

So what do we see? Tatum and Jaylen are actually driving to the rim more this season, but they are getting to the line less. Kemba is down in both areas. So while their whistle is in line with everyone else this season, their results are down from last year. That maybe helps explain why Tatum doesn't always play to contact. It's almost like he already knows that even when he drives, he's not going to get that call so he instead opts to play away from contact. That's bad.

My next question was how does this impact the team as a whole when it comes to FTA. Essentially, nothing is different from this year compared to last year. They rank 19th this year (21.2) compared to 18th last year (23.2). Just 2 FTA less a night. The real issue is their FT% has tanked from 5th last year to 23rd this year. So not only are they getting to the line slightly less, but they are missing a whole lot more. 

As a team, we're actually seeing the Celts drive more (47.0) this season compared to last year (45.6). Who saw that coming? The idea that they are doing nothing but settling for threes and aren't aggressive actually isn't the case at all. Which brings me to my next topic

Offense - 3PT shooting

This is obviously the hot topic coming off of last night. Lot of fans are mad at their offensive approach when it comes to shooting threes. Here's what the data actually shows 

Their 3PA is virtually identical compared to last year at 34.7 vs 34.5. The approach of a top 5 offense has not changed in this regard. In fact, they are making slightly more 3PM and shooting a slightly better 3P% this season compared to last as a team. This offense was 13th in the NBA in both 3PM and 3P%. This year, it's 12th and 13th.

So, not only has the 3PT shooting been slightly better as a team, but they are also driving to the rim a little bit more as well. You can see where that gets confusing. 

In terms of their Ortg, again things are virtually identical. A 113 rating this year vs 112.8 last year. That rating was good enough for 4th last season, this year it's 12th. Of the top 12 offenses, 8 are out West. The Celts currently have the 4th ranked offense in the East, slightly trailing the Hawks. The Bucks are still a wagon and the Nets have obviously exploded. But all things considered there hasn't been that big a drop off in their rating which ended the year at #1 in the East.

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Offense - Isolation

This is the big one. We all get frustrated when it comes to this team's reliance on isolation basketball. Mostly because they stink at it. I would argue that their issues offensively have little to do with their three point approach or this idea that they aren't driving to the rim enough. I find that it's here where the biggest issue lives. 

Jayson Tatum's iso% has increased from 15.8% to 18.7% while his production dropped from 1.0 ppp/40% to 0.84/35% 

Jaylen's iso% is the same 7.4%, but his prod is down from 0.82/37% to 0.77/36.5% 

Kemba is iso-ing less at 4.5% vs 6.7 but his iso prod has fallen at 0.68/22%

Smart's iso% has jumped slightly from 6.2% to 7.3% with his production dropping slightly from 0.81/33% to 0.79/38%

Those are your top 4 offensive options, so what does it tell us. Tatum has taken a fairly large step back in his iso offense while having the biggest jump in iso%. Yesterday's first half was a great example of that. Jaylen is the same, but the production is down. It's nice to see Kemba doing it less, but when he does it, it's beyond awful. I'd put Smart's approach at mostly a wash. Slightly lower in points per possession, but he's shooting better in iso situations despite the increased frequency.

So it then makes sense when you see that as a team the Celtics iso% has gone up from 6.7% to 8.0%, but they've dropped big time from the 86th percentile last year to 37th this year. So for me, it's not so much that everyone is doing nothing but iso, it's more that whoever does try to iso stinks at it. The fall off from Kemba really hurts. The fact that Tatum does it more and is less effective doesn't help. 

Now part of this could be the fact that in certain lineups, those guys are forced into playing this way. I'll allow that. But the sample is large enough to where they just have to accept this is not a successful approach for whatever reason this season. 

Offense - Assists

You would then think that if they are running more isolation, the problem is a lack of ball movement compared to a top 5 offense last year. That's also not really true. Last year they ranked 25th in the NBA at 23.0 assists per night. This year they rank 24th at 22.9 assists. This idea that the issue is a lack of a playmaking point guard doesn't really hold up. It certainly didn't impact them last year with basically the same roster, including losing a playmaker like Hayward this year. 

Offense Conclusion:

This is not where I would put the majority of the blame for the Celts issues this year. They're basically repeating what proved to be a top 5 offense while also driving to the rim more and shooting slightly better from three. The regression in isolation offense is an issue for sure, but it's not so drastic where suddenly Brad's offensive system is the issue.

Which brings me to the real problems

Defense - Perimeter

Here it is. You want to know the biggest reason this team has taken a step back, look no further than their perimeter defense. A staple of the Brad Stevens era during his entire tenure has turned into a complete disaster. 

Opponents are making 13.0 3PM a night against the Celts this season, good for 19th in the league. They're shooting a solid 37.3% which is also 19th. Last year? A much better 11.8 (10th) and 34% (2nd). That's a giant difference. The issue with such a drop off on the perimeter isn't just what it's done in terms of 3PT defense. When you're weak up top, it allows you to be exposed in the paint. I'm not talking about rim protection, but guys scoring in the paint. The Celts allow 43.8% shooting in the non restricted area. That's the 7th worst in the NBA. While still OK, we've seen this impact their overall opponents points in the paint. Last year they were the 3rd best team in this area at 43 points. This year, it's 9th at 45%.

Basically what happens is when there is no resistance up top, guys are able to get into the paint at will. When they aren't taking those shots and instead are moving the ball, due to the Celts being forced to over help and rotate, that's where you're seeing teams be able to load up from behind the arc on wide open threes. It's a chain reaction of sorts. 

We just aren't seeing the best individual defenders on this roster make an impact on that end. When it comes to their defended FG%, guys are shooting 45.7% with Marcus Smart defending. With Tatum it's 46.4%. Semi is at 50%. Kemba is at 47.5%. Grant is at 45.4%. Jaylen has been OK at 42%, but he can't be the only one showing up on that end. 

Compare that to last year and you can see the issues. Smart was at 42.8%, Semi at 42%, Tatum at 43%, Jaylen at 43%, Grant at 41%, shit even Kemba as was at 44%

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This is why we keep hearing Brad and Ainge talk about the players needing to be more consistent and actually play with energy and effort. The individual defense across the board from their perimeter players has been mostly dogshit compared to last year.

Most shocking? Rob has gone from 40% last year to 46% this year, so it's not like he's been the savior either.

Team Defense

That's why when you add it all up, it makes sense why the Celts suddenly have the 21st ranked defense. Their rating sits at 112.2, and they are another bad week from dropping even further. 

Last season at 106.5, this roster had the 4th best defense in the NBA. Nothing has changed in terms of the system. All these guys have been around long enough to understand what to do. But when the energy and effort isn't there, guys aren't providing resistence on the perimeter, everything falls apart. 

Defense Conclusion:

The dropoff when it comes to both individual defense and team perimeter defense is the biggest culprit of this team's struggles. Their rim protection is fine, but they aren't asserting themselves on that end when it comes to the perimeter. That's what allows their defense collapse to snowball. As you can see, it's an across the roster issue.

Clutch Time

Without a doubt, the Celts have been the worst clutch time team in the league this year. They are 11-21 in clutch time games. As a team they shoot 40/22%. The individual breakdown of their best players in these moments is brutal

Tatum: 45/31%

Jaylen: 41.9/29.4%

Kemba: 17/15%

Smart: 30/11%

That's just killer. This is important because as we know, since this team doesn't defend, they find themselves in a lot of clutch time games. Look at how drastic of a change this is compared to last year

Tatum: 50/35%

Jaylen: 44/41%

Kemba: 34/41%

Smart: 37/25%

With this same group, playing the same style, we saw a team with the 8th best clutch offense, 13th best clutch defense, and 12rd best clutch rating. Not great, but at least average. This year? 

28th offense, 18th defense, 23rd net rating

So what happens in these moments? A lot of it is falling into the bad isolation habit. Their AST% of 43.2% is 26th in the league. They aren't moving the ball in these high pressure situations. Last season they were 3rd in the NBA at 60.3%. Part of this is not having a guy like Hayward in the clutch for playmaking, but the other part is the best players on this team are forcing things offensively while taking a massive step back in their efficiency. 

Let's take Hayward out of it. Look at how much this shit has dropped

Smart Clutch AST%: 34.2% to 25%

Kemba Clutch AST%: 26.4% to 18.8%

Tatum Clutch AST%: 20.8% to 15.8%

Brown Clutch AST%: 3% to 4.0%

Outside of Jaylen, everyone else has taken a big step back in favor of more isolation/shooting, and look at their percentages again. That explains why this team stinks in the clutch. They are not playing unselfish basketball. As a result, everyone is forced to take tougher shots, which lowers their efficiency. 

Overall Conclusion

Offensively, I actually don't see any glaring issues outside of a slight uptick in isolation. But that changes when it comes to cluth time minutes. That might be a small part of the game so it doesn't impact their overall numbers, but it's the most important part. That's why I feel like people might think the offense is a problem. Big picture it isn't, but in that specific area it's massive.

For me, it's the regression defensively that has plagued this season. Even when guys are in the lineup, they've pretty much regressed across the board.

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But this also tells me things are fixable. Defense is all about energy and effort. We've seen this group do it before. It's not like their is a fatal flaw in how they play, it's just that they are not executing to the level we are used to seeing for a wide variety of reasons.

So as you can see, it's a little more complicated than just "The Celtics suck". There are issues that need to be addressed, but hopefully this helps you understand what has been a truly weird season.