By Matthew Geagan, CBS Boston

BOSTON (CBS) — Danny Ainge had a difficult decision to make Thursday, shipping out Celtics center Daniel Theis in a three-team trade just before the trade deadline buzzer sounded in the NBA. Theis had a solid four-year run with Boston after the team signed him out of Germany, going from a relative unknown to a quality NBA player.

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“I really appreciate Theis and all he did for us,” Ainge said Friday morning. “He got better as a Celtic; no one knew who he was and now the NBA knows who he is.”

But Thursday’s trade was two fold for Boston. In moving Theis, an impending free agent after the season, the Celtics got under the luxury tax threshold after acquiring Evan Fournier and his $17 million salary earlier in the day. That was likely the most important factor of the deal, but just as important is the playing time it frees up for young big man Robert Williams.

Williams has been one of Boston’s few bright spots during an otherwise disappointing season, finally emerging as an impact player for Boston. The 23-year-old’s progress had been limited due to a rash of injuries since the Celtics took him at the end of the first round in 2018, but he started to burst out during last season’s bubble action in Orlando.

The man known as “Time Lord” has made his case for more playing time this season, averaging 7.7 points and 6.4 assists over 37 games off the bench. He’s averaged of 17 minutes per game this season, and has been getting even more run as of late. Williams has eclipsed 20 minutes of action nine times since mid-February, including a career-high 27 minutes in Memphis earlier this week. He’s rewarded the Celtics with some energetic dunks on offense, a slew of rebounds, and some solid defensive play.

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But for Williams to continue on his upward trend, he needs more playing time. Theis, despite all the good things he did in the Boston starting lineup, was a bit of a roadblock in that aspect. Now, Williams will have a much more expanded role, which should allow him to continue his ascension.

“Rob has been our best defensive center so far this year. I think everyone knows that,” said Ainge. “He has improved a great deal, come a long way defending pick-and-roll, and still has a long way to go with an even bigger upside ahead of him. It’s going to be a bigger role for Rob at this moment.”

The Celtics have been greatly lacking on the defensive end of the floor this season. For a team that has been firmly entrenched as one of the NBA’s top five defensive teams the past few seasons, it’s extremely concerning. But as Williams progresses on that end of the floor, so too should Boston’s team defense. At least that is the hope going forward.

With Tristan Thompson still out due to Health and Safety Protocols, Williams will be logging some starts for Boston. He’ll likely be No. 2 on the depth chart when Thompson returns, with newcomer Mo Wagner behind him.

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But the door is now open for even more Rob Williams the rest of the way. He’s been an instant injection of energy whenever he’s stepped foot on the floor, something the Celtics have desperately needed for much of the season. It really wouldn’t surprise anyone if Williams becomes Boston’s top big man by season’s end, and he’ll have every opportunity to claim that spot over the final months of the season.