Boston’s Big Problem: Aron Baynes’ Numbers Reveal a Startling Trend for Celtics Smallball

The Celtics have a big problem.

No, literally they have a big-man problem.

Heading into this season, after Jaylen Brown and Jayson Tatum emerged as incredible young weapons that carried the team to a No. 2-seed and the Eastern Conference Finals (and a Game 7 vs. LeBron at that), the main question was "How can Brad Stevens fit all this talent in on this team?"

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The answer was smallball. After last year's success, the Celtics decided to put their five "best" players on the court to start games: Kyrie Irving, Jaylen Brown, Gordon Hayward, Jayson Tatum and Al Horford at center.

There was zero reason to think this wouldn't work.

Horford played center for a decade in Atlanta and played it brilliantly. This lineup put two playmakers in Horford and Hayward on the floor, alongside three individual scorers in Irving, Tatum, and Hayward, with multiple guys to fill in gaps coming off the bench.

Made a lot of sense at the time and it still does, honestly. The danger with early season, small-sample results, is people will overreact.

But boy, has that lineup been bad. It currently features a 90.8 offensive rating and is a net -4.2 per 100 possessions. That is the basketball equivalent of trying to win a battle against robot ninjas with rocks and pointy sticks.

There are a number of reasons for this start, and everyone's got a theory. The starters have shot really poorly on good shots. The team lacks toughness. The shot selection has been terrible. The team has too many guys looking to get their own instead of playing a role, especially the young players.

I've seen almost all of the Celtics' games this season, and all of those reasons seemed to have played a part. There is, though, an interesting trend that bears discussing.

And his name is Aron Baynes.

Most of this column was written Sunday and Monday before the Celtics' loss to the Hornets. Brad Stevens actually moved Baynes into the starting lineup. Baynes was a minus-7 in seven minutes, so the early returns were bad.

But playing so few minutes, it's hard to get any real sense of it, and most of the trends you'll read below hold up.

The Stats

We're going to go point-by-point instead of using a chart, because some of this stuff you just have to put into context.

STAT: Al Horford has only played 21 minutes, total, with Aron Baynes this season. 

Those 21 minutes were awesome, by the way. They outscored their opponent by 11.4 points per 100 possessions, even after the Hornets game. They ruled for those 21 minutes.

In the 480 minutes Horford has been on the floor without Baynes, the veteran big man has a net rating of minus-0.7. This is your second-best player, your All-Star franchise guy … and you have a raw box score +/- of minus-7 with him on the floor.

That's a concern.

STAT: The "kids" are 23 points worse in net rating without Baynes. 

Jaylen Brown and Jayson Tatum have played 42 minutes with Baynes, and have a net-rating of plus-8.3 In 237 minutes, they have a net rating of minus-1.3 without him. If you prefer the raw numbers, they go from plus-12 to minus-8 without Baynes.

And again, we don't know enough about how the team performs with a "big lineup" this season, as Brown-Tatum-Horford have only played 20 minutes with Baynes. But we do have last year's data.

Brown-Tatum-Horford lineups were a plus-4.1 in net rating last season without Baynes. They were plus-14.3 per 100 possessions with Baynes. We have a lot of evidence those lineups worked last year.

They even had an offensive impact: Their offensive rating was 111.0.

STAT: Gordon Hayward's numbers are unaffected by Baynes.

Hayward's numbers are basically the same on both offense and defense with Baynes on the floor. There's very little impact there.

STAT: Terry Rozier's numbers fall off a cliff (13.8 points worse per 100 possessions) with Horford and without Baynes. 

In 132 minutes, Rozier shoots 42% from 3-point range with Baynes on the floor and 31% from deep with Baynes on the bench.

Rozier has struggled quite a bit this season, so anything that helps him should be a priority.

The Impact

So there are a lot of ways to try and decipher this. You can argue that Baynes is just padding stats in garbage time, but Baynes actually plays his fewest minutes per game in the fourth. You can argue that it is just noise, but we're seeing the same trends over and over across different players. Everyone else is playing better with Baynes on the floor.

So why does this work better with Baynes? A lot of this gets into why I wind up putting so much stock into the ON/OFF numbers. They tell you what has worked in the most fundamental elements of the game, scoring, defending and outscoring/being outscored by the opponent.

They don't tell you anything predictive in this small a sample, just what has happened so far. And for whatever reason, the Celtics have played better with Baynes and particularly with Baynes and Horford together.

You can dig into various metrics, but there's also an intangible feeling that these numbers point to. We can postulate that it's rhythm and continuity after last year. We can point to things like this, showing Baynes is a phenomenal screener:

Gordon Hayward just gets so much room to work as a result of Baynes.

And on this one, even though Kyrie Irving has to go to a fadeaway against a taller defender, he's super comfortable in this spot. Baynes eradicates the defender with this screen.

Baynes averages 6.4 screen assists per 36 minutes per NBA.com's hustle stats. Now, some of that is because he only plays 14 minutes per game. He comes in, hammers dudes, and goes out. But that's an example of how he impacts the game.

He absolutely helps with spacing, too. His ability to hit from distance is one reason why the Sixers have such a hard time matching up with him.

Stevens clearly recognized this, which is why Baynes went back into the starting lineup. Except he clearly yanked him quickly in that game despite Charlotte playing a more traditional frontcourt.

In the five games Baynes has played more than 15 minutes this season, the Celtics are 4-1, and he is a plus-38 in 91 minutes.

There are a lot of solutions for the Celtics. Shoot better, make more open looks (which is a disturbing trend across the years as an issue for Brad Stevens teams, but that's a story for another time).

Get guys to adapt to their roles a little more. Get Horford going a bit more. Get Hayward back up to speed. Have Tatum forget everything Kobe Bryant taught him this summer. You know, normal things.

But it's worth noting, even if Baynes isn't some fix-all solution (which he's not) that it does indicate a central issue.

The smallball lineups aren't working well right now, and from last year through the start of this year, bigger lineups with Horford and another big (specifically Baynes) look like they make everyone more comfortable and confident.

Those are key for an offense, and they probably need to explore putting a little more into those lineups.

After all, no Baynes, no gain.