The Celtics’ high usage solution

Usage might seem like a complicated stat to the indoctrinated, but it’s fairly simple. It’s a measure of how often a player contributes to the end of a team’s single offensive possession, whether that’s a shot or turnover. It measures how many of a team’s possessions involve that player either shooting, assisting, or turning over the ball.

The point of this stat is to see how often a player is “using” his team’s offensive possessions. While it’s not perfect, usage can help give an idea how ball dominant a player might be. Examples of high usage players would be league leaders like James Harden, Joel Embiid, Devin Booker, Giannis Antetokounmpo, Lou Williams, and LeBron James, players who bear the brunt of their team’s responsibilities on the offensive end.

An “average” usage percentage is considered 20% (as in five players on the floor divided by 100%), and the Celtics have four players with an above average usage on the team. They are in order: Kyrie Irving, Jayson Tatum, Jaylen Brown, and Marcus Morris. I went into this exercise with a hypothesis that there might be detrimental affect to having too many high usage players on the floor at one time. I went through the lineup data trying to find out if my theories held any water. Here’s what I found.

All lineup data courtesy of the NBAWowy tool at AddMorefunds.com.

Some quick disclaimers about this data.

1. When you get into criteria that is this small, sample size becomes an issue. I’ve included possessions with this data so everyone can see just exactly how big of a sample size we are dealing with for each set of numbers.
2. Strength of competition plays into these numbers slightly, particularly in Brown’s case. As the Celtics’ star player, Irving primarily squares off against the opposing team’s best player in the starting lineup. On the other hand, Brown, who is now coming off the bench, might see more run against opposing end-of-rotation players. It is worth noting, however, that by the same token, Brown is primarily playing with Celtics’ bench players.

While it might be self-evident from glancing at the chart, there is a pretty clear finding from sorting through this data. The Celtics, by in large, preform better when there are only two high usage players on the court, particularly if one of them is Irving. There are several other mini-trends, particularly regarding the overall value of Jayson Tatum, and the defense of Marcus Morris, but more usage seems to be less when it comes to this year’s Boston Celtics.

Extrapolating these theories out to other Celtics phenomena shows some consistency and patterns. For example, the insertion of Marcus Smart and Marcus Morris into the starting lineup can be viewed as the Celtics cycling in lower usage players. Morris is a lower usage player than Brown and Smart (despite his high turnover rate) has one of the lowest usage rates by non-bigs in the entire league. Last year’s surprise run to the conference finals came after Irving’s injury, but it also came after Brown and Tatum’s usage jumped from 18.9% and 18.0% respectively before the All-Star break to 23.5% and 22.2% after the All-Star Game.

This year has been an averaging out of those numbers, as Irving and Morris’s usage have dropped since last year, while Brown’s and Tatum’s have risen, although not to the same level they enjoyed during the Celtics surprise playoff run last season.

David Richard-USA TODAY Sports

It’s easy to misunderstand these numbers as “the Celtics, and especially Rozier, are better without Kyrie Irving” but that’s absolute foolishness. Rozier has been a bit of a magic-eye puzzle for the Celtics this year, particularly since he anecdotally seems to play well when starting in games that Irving rests. However, a closer look will show that the Celtics have been a net negative when Rozier is out there without Irving. On the flip side, however, Celtics lineups have an identical differential when Kyrie Irving plays with Rozier, versus when they play without Rozier.

What gets addled when talking about Rozier’s role on the team backing up Irving, is that Rozier is a “middle of the road” usage player on the Celtics like Hayward and Horford. Conflating him with Irving because they both bring the ball up the floor and are about the same height misses the point. The Hospital Celtics of last year, while injured, still had a team that made sense usage wise, even after losing Hayward and Irving. The Celtics were still able to keep low usage players like Baynes and Smart healthy, and go through large stretches where the high-usage players had run of the show.

The Celtics are currently navigating a question of usage problems, which I guess is sort of inline with the “too much talent” hot take that has haunted the Celtics all year. However, things like trimming the rotation, and having healthy low usage players like Aron Baynes available can help the Celtics navigate this easier. While it’s unlikely to see, something like trimming Morris’s minutes in the playoffs might give the Celtics a more direct path to maximizing many of the other Celtics’ talents.