The Celtics' 2023 playoff journey begins Saturday afternoon against the Atlanta Hawks, and all eyes will be on Jayson Tatum and Jaylen Brown as they aim to carry Boston back to the NBA Finals.
But if you ask many in and around the organization, more eyes should be focused on No. 44 in green.
While Robert Williams' stats don't jump off the page -- he averaged 8.0 points, 8.3 rebounds and 1.4 blocks in 35 games played for the Celtics this season -- the fifth-year big man is integral to their playoff aspirations.
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"Rob Williams is absolutely the X-factor for this Celtics team," Celtics sideline reporter Abby Chin says in the video above, which is part of NBC Sports Boston's "The Difference" series spotlighting what separates the 2022-23 Celtics from last year's squad.
How does Williams change the equation for Boston despite being the team's eighth-leading scorer? It all starts on defense, says former Celtics point guard and NBC Sports Boston analyst Eddie House.
"(The Celtics' defenders) can be more aggressive on the perimeter knowing that you have a guy who can clean up a mistake or make somebody make a mistake," House explained.
Williams is an elite interior defender who leads the Celtics in blocks, but he still makes an impact when he doesn't touch the ball. Opponents shot just 43.7 percent with Williams as their primary defender this season; only two players in the NBA (Jaren Jackson Jr. and Garrison Mathews) limited their opponents to a lower shooting percentage (minimum 35 games played).
Ex-Celtics forward and NBC Sports Boston color analyst Brian Scalabrine noted Boston is an "elite defensive team and an elite defensive rebounding team" when Williams and Al Horford are on the court together, and the numbers back up his point: The Celtics boast a stingy 103.1 defensive rating and an 80.2 percent defensive rebounding percentage with Time Lord and Horford on the floor.
Boston will need Williams to assert himself on the boards against Hawks big man Clint Capela, who ripped down 21 rebounds (eight offensive) in Atlanta's play-in tournament upset of the Miami Heat. But even if Williams isn't posting double-doubles on a nightly basis, his ability to keep the ball moving on offense and get in opponents' heads on defense can make a significant impact.
"The presence that Rob brings at the rim on both ends of the floor is invaluable," Celtics Insider Chris Forsberg says. "Just his presence alone changes this team and the way it plays. There's a different swagger for the Boston Celtics when Robert Williams is on the court, and it all starts with his presence."
Injuries have been an issue with Williams, who missed more than half of the team's games this season and has had multiple procedures on left knee. Unlike last year, however, the 25-year-old appears healthy entering the postseason, as head coach Joe Mazzulla worked on stretching out his minutes near the end of the regular season.
The Celtics boast one of the NBA's best offenses this season thanks in part to the offseason addition of Malcolm Brogdon and the resurgence of Derrick White. If Williams can stay on the court and bolster Boston's defense, the sky is the limit.
"Will they flip a switch and do it the way they did last year with the better offense and the better shooting and lower turnovers? If they do, you can stamp it right now, you heard it here first: They're gonna win a championship," Scalabrine said.
Check out NBC Sports Boston's full feature on Williams in the video player above.