Xavier Tillman Managing Knee Pain and Says He’s 75% Acclimated to Celtics

ATLANTA — Xavier Tillman Sr. sat at his locker, rolling his foot on a ball to activate his knee before the second game between the Celtics and Hawks — preparing to play after missing the first last Monday. It marked Tillman’s first game missed for physical reasons since he sat out four before the all-star break with left knee swelling.

Tillman told CLNS Media that the return of that swelling, which he reduced with medication, will be something that he manages for the rest of the season. He sat out his last four games with the Grizzlies before they traded him to Boston in February, a move considered more precautionary as they weighed moving him. Tillman had said in Chicago last month, before his Celtics debut, that the knee ailment that forced him to miss 10 games in the fall wasn’t related to the latest, but he’s now played 61 games, at most, in his career. He said he’s doing good now.

On the court, the big man considered himself 75% acclimated to the Celtics, who utilized him early that night in Atlanta before he suffered a bloody nose chasing a free throw rebound. He went on to receive depth minutes over Luke Kornet again against the physically imposing Pelicans, who he helped limit to 92 points, the fourth-fewest allowed by Boston all year, in 10 minutes that the Celtics won by seven points. Tillman scored three points on 1-for-3 shooting.

“The last 25% is knowing tendencies of my teammates and actually, truly, knowing all the plays,” Tillman told CLNS. “I’m still iffy on all the sorts of plays, but definitely, 75% (acclimated), I’d say … I think (the last 25% is also) breaking old habits, like what I used to do back in Memphis versus here. I mean, that’s really it, versus me actually not knowing. It’s I wanna do something without thinking about it that I used to do, that is different than what we do here. So just kind of X-ing that out and really locking in our principles and how we like to have our offense, our formations and stuff like that.”

Tillman thrives on defense, and his production, at least visually, on that end pops even if the numbers don’t over his limited playing time since arriving in Boston. Opponents shot 52.6% against Tillman through his first 13 games, the only player on the current roster who’s given up over 50% shooting in sometimes-wonky tracking stats covering who scores on whom. Some of that involves his shift to the four in a defense that typically switches across the perimeter. Tillman improved to holding Zion Williamson to 9-for-25 (36%) in four meetings this year between his two teams. A guard like DeMar DeRozan, however, hit both shots he took over him last week.

The advanced stats still sing Tillman’s praises. The Celtics have posted a 109.0 defensive rating in his minutes, better than the team’s overall 110.7 for the season, and his +14.2 net rating ranks above Derrick White’s +13.6 as the best mark among the roster’s regulars. Only six players rank above Tillman in defensive expected plus-minus (+3.2), two of them the injured Marcus Smart and Joel Embiid, while his rating compares favorably to defensive player of the year candidates Victor Wembanyama (+3.4) and Alex Caruso (+3.6). It’s also worth acknowledging how many experimental minutes Tillman played to begin his tenure, including alongside Kornet.

“Our big’s versatility is one of the most important things for our defensive system,” Joe Mazzulla said. “Al has led the charge in that. Luke has really grown in that versatility. The ability for bigs to play alongside each other and execute different coverages, and guard different matchups, is super important. That was the process of when we got X of being patient and taking time, initiating him into the system, so that it’s seamless when it does happen. His ability to play alongside Luke, like in the Utah game, really comes down to his ability to handle different matchups defensively, handle those coverages, communicate and take pressure off the other big, but also show the versatility to make sure our defense stays where it is.”

“We waited for him to understand the language, understand the dynamics of (the defense). Obviously the staff, doing a good job getting on the floor with him and walking through all the rules and areas. Him hearing, within the first few shootarounds and the film sessions, getting a clear expectation of what the expectations are. Then, the understanding that every possession changes, so having the open-mindedness to be able to pick up on that.”

The combination of Al Horford and Tillman appears the most promising, with Horford praising how Tillman takes pressure off him on the defensive end. Horford being able to do the same on offense for Tillman allowed the pair to post a +14.7 net rating in their first 49 minutes together. Playing at the four pushed Tillman to the corner often to begin his time with the team, where he received a shot or two each game, culminating in 3-for-17 (17.6%) shooting. He laughed when told that percentage, you’re talking about percentages? he said. I feel great about it. I’m only getting 1-2 per game … I’m not sweating that at all.

To counteract that, Boston added in some off-ball screening to get him involved in actions outside of the high pick-and-roll that Kornet, Horford and Kristaps Porzingis will often initiate. Tillman also receives free rein to chase offensive rebounds and post up, the latter something he expected to do more often than he did in Memphis. Those opportunities could still come, it’s early in his tenure and work back from whatever knee soreness he’s feeling. The prospect of playing big, having a matchup center for physically-imposing centers and playing multiple lineups intrigues Boston, but to this point Kornet received favor as the one out of the two with years of institutional knowledge, the ability to set screens how they want to and having made progress as a roller, finisher and offensive rebounder to where those areas became strengths.

For Tillman — being able to hold up in more defense coverages could give him the edge if he can learn the offense in time. He becomes an unrestricted free agent at 26 this summer.

“We spend a lot of time as bigs on the wing here and back in the day, it was either at the top of the key or in the corner,” Tillman said. “So sometimes I catch myself running on top of the top of the key or I catch myself running to the corner where like no, no, no, you gotta run to the wing. That’s the simplest thing. It is a lot different. I’m used to setting a lot of screens. There were periods throughout this season where I was in the corner a decent amount, but for the majority, I was in the action, versus now, being in the corners and stuff like that … (I’m) pretty comfortable. As the games go on, I’m always learning something new about the team and how they operate through different situations … it’s continuous, in terms of how much I’m learning.”