Can Robert Williams play his way into Celtics playoff rotation?

No one wanted to see the NBA season come to a halt in March, but the extra four months of rest likely did a world of good for some players that could have used some extra time to rehab. Robert Williams would be one of the names you could put on that list.

The 6-foot-9 center had been sidelined for 38 games midseason with a hip bone edema. He had played in 45 minutes in four games since returning to action on March 3 but the tight time window in an NBA schedule gave him limited time to practice with teammates ahead of his return.

Now, it’s a level playing field for all involved after a four-month hiatus. Williams has been a full participant in Celtics practice over the past three days and used the extra time off to improve himself and his body.

“I actually feel like I got a little bit quicker, a little bit faster,” Williams said Sunday. “But being out those three and a half months, it gave my body time to heal. I got some good treatment, some good work in, and I’m ready to prove it on the court.”

Staying healthy will be the biggest challenge for Williams in the bubble. He’s missed over 40 games to injury in each season of his NBA career so far, making one of the biggest question marks about him (durability + injury history) in the 2018 NBA Draft rear its head.

The Celtics have not been shy about giving Williams opportunity though when he’s been healthy, particularly this season. The big man is averaging 4.3 points and 4.7 rebounds in 14 minutes per game and even saw crunch-time minutes in key matchups during November in an attempt to add speed and athleticism to the C’s defense.

“I think our defense can go up another level,” Marcus Smart said when Williams is on the floor. “We got somebody back there that can protect the rim. No offense to the other guys on our team, but Rob is a different type of freak of nature when it comes to athleticism, and the ability to go and change shots at the rim. So that allows us to pick up our pressure a little bit more as guards. And really, really, really just give the opposing team problems.”

The problem so far is that Williams, beyond some flashes, has not produced the kind of consistency needed to be trusted as a rotation piece yet in year two. The numbers are actually a little bit concerning on that front (albeit in a limited sample size of 323 minutes). Consider this:

The Celtics’ defense is at its worse when Williams is on the court, allowing 108.6 points per 100 possessions, a significant dropoff from other centers on the roster like Daniel Theis (104.1). Williams isn’t completely to blame for that issue (he’s not the only one on the court in those minutes) but him being on par with another defensive weak link (Kemba Walker) in this metric does not bode well for him. Defense is supposed to be his biggest strength and the metrics have not matched up yet on that front.

Williams biggest weakness to date? The Celtics’ rebounding when he is on the floor falls off a cliff, particularly on the defensive end of the floor. Williams may be a high flyer, but he lacks great upper body strength and the discipline to stay on his man down low, chasing blocks instead. That opens the door for offensive rebounds for opponents. The C’s defensive rebounding rate (66.2%) is the worst in the league when Williams is on the court and a tremendous drop-off form compared to when guys like Daniel Theis (73.9%) and Enes Kanter (74.5%) man the middle.

A more seasoned player will be able to spot these issues on film and stay more consistent with their assignments. That’s something that Brad Stevens is optimistic about doing with another year under his belt, to give the C’s the ability to let him play to his strengths.

“He’s always been able to protect the rim at a high level, and I thought he was really improving early on in the season before he got hurt with a lot of pick-and-roll coverages,” Stevens said of Williams. “When he came back, obviously there is going to be a little bit of a transition period, but now that we’re back and everyone is in a transition period, you can tell that . . . he looks like an older player now, finishing off his second year but basically entering his third.”

Opportunity will be knocking for Williams, particularly during the seeding games as veterans are rested. The Celtics will be looking to see whether Williams has been able to make the necessary strides with his defense in order to get him in the mix for the 15-18 minutes per game at backup center that will likely be split among Kanter, himself and Grant Williams in the postseason. The upside is higher than anyone in that group and team sources remain very optimistic to BSJ that Williams will be able to put it altogether, raising the C’s ceiling in both the short and long-term at the center position.

With the team likely financial limited going forward with a flattened cap due to a pandemic and huge salary commitments to players in their wings and backcourt, having a player on a rookie deal transform into a starter-level center would be a big boon to the team’s plans.

“He’s got great vertical athleticism, he’s a good communicator on the court, knows what we’re trying to do at both ends, he gets to the rim quick on rolls, hopefully, he maintains his good health,” Stevens said. “At the start of the year, one of the things we wanted to do was have a lot of flexibility at that spot. The guys available most of the year have done a great job. When he’s had his opportunity he’s really had some moments. We’ll hopefully be healthy and hopefully, have everyone be impactful.”