The Celtics are due for rotational changes: Frontcourt edition

Earlier this season, head coach Ime Udoke mentioned that he was going to look at switching up his rotations. These comments came after the Boston Celtics got dominated by the Phoenix Suns in the middle of December during their now infamous west coast trip.

“It’s [potential lineup changes] something we’ll definitely take a look at. Twenty-seven games is a good sample size.”

While the immense number of COVID-related absences forced him to switch things up, no long-term changes have been made yet. Both Al Horford and Robert Williams have started every game they’ve played in this season. The duo has been great on the defensive end, but the floor spacing they bring has been questionable at best.

Williams doesn’t shoot threes. He’s attempted two threes in his entire career and he missed them both. And although Horford’s been a great stretch big in the past, his shot hasn’t been on the money this season. He’s shooting 27.8 percent from deep on the season.

Prioritizing defense has been at the top of Udoka’s to-do list, but it may be time to explore some offensive options — namely, Grant Williams. Inserting Williams into the starting lineup would improve Boston’s floor spacing ten-fold.

In wins this year, the Celtics have shot 37.3 percent from deep. On the other hand, they’ve only shot 20.1 percent from three-point range in their losses. There’s a clear correlation between good shooting and winning basketball games for the C’s this season. This is where Williams comes in.

Cleaning the Glass has a list that ranks all lineups that have played at least 100 possessions together this season based on various factors. One of those factors is points scored per 100 possessions, which helps measure how effective an offense is. The Celtics have four lineups in the list of 100, and only one of them ranks in the top 70 in terms of points per 100 possessions. That lineup ranks sixth, and it includes Grant Williams. He is not included in any of the other three lineups.

This year, Williams is shooting 42.6 percent from behind the arc. In addition, he’s shooting 52.7 percent from the corner - one of the best marks in the entire league. H’s been a crucial part of Boston’s offense this season, and they win more when he’s on the floor.

When Williams plays at least 27:30 (yes, an odd number), the Celtics are 8-3 this season. When he plays at least 30 minutes, Boston is 5-2. Meanwhile, when Williams plays less than 16 minutes or doesn’t play at all, the C’s are 5-9. Udoka even threw all three bigs into the starting lineup recently, and it worked out fairly well. They started alongside Smart and Brown against the Suns.

Adding Williams in the starting lineup would not only put an extra shooter on the court, but it would open up the floor for Boston’s stars. With Williams simply standing in the corner, the defense is forced to leave a body on the perimeter. They are unable to cheat into the paint, and if they do, Williams will nail the shot and punish them.

Take a look at this play. Tatum gets a screen from Williams and Bryn Forbes switches onto him. This leaves Keita Bates-Diop in the corner to defend Williams. Instead of helping on the drive, Bates-Diop is forced to sit in the corner to deny a kickout.

Meanwhile, look at the spacing on the possession below. With both Horford and Robert Williams on the floor, the paint is packed. Horford sets a screen and immediately rolls to the rim, but since he’s sharing the floor with Williams, it puts two bigs down low. This allows both Derrick White and Keldon Johnson to contest Tatum at the rim, where he misses the contested layup.

Williams’ gravity is just as important as his actual shot-making ability. He creates more space for everyone else on the floor just by being out there. That being said, his ability to knock down shots is obviously crucial as well.

When defenders do decide to leave Williams in the corner, he makes them pay. This goes back to the simple statistic of, “he shoots a better percentage than Horford,” but just look at the defenders’ reactions. When Keon Johnson leaves Williams in the corner, he immediately realizes his mistake. Johnson rushes out to try to get some sort of contest on the shot.

In that same game, look at how the LA Clippers react when Horford gets an open look. Marcus Morris and Luke Kennard both choose to guard Payton Pritchard on the drive. This leads to a wide-open look for Horford. But unlike Johnson’s closeout attempt on Williams, LA doesn’t even bother contesting Horford.

This wasn’t just a one-time deal, either. It happened throughout the entire game.

Horford would finish that game 0-for-7 from three-point land.

All of this isn't to say that Horford’s a bad player and needs to get less playing time, but he's simply not an effective floor-spacer this season. Meanwhile, Williams has turned himself into one. Boston’s offense has struggled to remain consistent this season and having lineups on the floor that can’t shoot isn’t helping.

The biggest argument against starting Williams is that the team’s defense would take a huge hit. But while the lineup of Al Horford and Robert Williams has been phenomenal on the defensive end, Grant Williams has made huge strides as a defender this season. He’s able to stay in front of guards, battle in the paint with bigs, and Robert Williams even said that he’s their best communicator on the defensive end.

Not only is the offense worlds better with Williams on the court, but the defense doesn’t suffer for it. Udoka played him in the closing minutes of the Magic game over Horford, so it could only be a matter of time before he earns a spot in the starting lineup. During a time where the Celtics desperately need more shooting, why not throw the best shooter on the team in the starting five?