The Boston Celtics’ starting center job is up for grabs. Al Horford manned the position for the majority of the past three seasons, but the 33-year-old defected to the rival Philadelphia 76ers in free agency. Horford sometimes started at the four when head coach Brad Stevens inserted Aron Baynes into the first unit, but the latter was traded to the Phoenix Suns.

Addressing their needs at center, the Celtics signed Enes Kanter to a two-year, $10 million deal. They also re-upped Daniel Theis to a two-year pact. But is either big man equipped to handle playing the five with the first unit on a consistent basis?

Kanter is an excellent rebounder and scorer, but has come off the bench for most of his career because of his severe defensive deficiencies. Theis, the 6-foot-9 big man from Germany who tore the meniscus in his left knee in his rookie season in March 2018, looked slow on defense last year. He did improve his shooting, connecting on roughly 39 percent of his three-point attempts. But he got beat off the dribble far too often in his sophomore campaign, not looking nearly as quick as he did before he underwent knee surgery last offseason.

So who else will receive major minutes at center for the Celtics? Enter Robert Williams, known by many Celtics fans as “Time Lord,” the 27th pick of the 2018 draft who played well in limited minutes during his first pro season.

Robert Williams, Celtics

Williams, the 6-foot-10 former star of Texas A&M University, did not play much in 2018-19. He logged only 283 minutes in 32 appearances. But when he saw the court, he displayed his off-the-charts athleticism. A fan favorite, he wowed the Boston crowd by throwing down alley-oops and blocking shots.

In last year’s regular season finale, Williams helped the Celtics—who were resting their starters—to a road victory against the Washington Wizards. He secured a team-high 11 rebounds with two points and three blocks in 29 minutes.

Williams must demonstrate to Stevens that he is capable of leading the defense up front after flashing potential as a rookie. Williams, a defensive-centric big, must guard better against the pick-and-roll. The 21-year-old has plenty of time to enhance that part of his game. He has already established himself as a shot-blocker with the ability to protect the paint.

Williams, however, was a non-factor on offense last year. He has to develop some offensive skills other than throwing down jams. He looked lost when he got the ball with his back to the basket.

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Robert Williams

Looking to exhibit his talents and the strides he made from last year, Williams will take part in the Summer League. He played in one Summer League game last year, hurting his knee in just two minutes of action and being subsequently shut down until the regular season. Williams said he is “starving” to prove himself.

“I’m trying to get out here and play, Williams said on Monday. “I’m trying to showcase. Everybody’s trying to showcase, man. There’s a chip on your shoulder, always. Especially, not being able to play that much in Summer League last year, not being able to prove myself like I wanted. It’s another opportunity going in as a second-year player. Just got to keep that mentality.”

The Celtics are hoping he can excel in the Summer League and plan on giving him all the minutes he can handle. Scott Morrison, Boston’s Summer League coach, said Williams is expected to suit up for every game in Vegas.

Williams needs to show his growth on the offensive end this summer. If he can dominate this summer and show a better ability to defend the pick-and-roll, he could be in line for some serious minutes when the real games start up.

Robert Williams

Kanter will likely be Boston’s starting center when the 2019-20 NBA season opens. His superb rebounding (corralling 8.6 boards in 22.3 minutes per contest last season) will be a welcome sight for a club that ranked 22nd in rebounding last year.

Nonetheless, Williams can challenge Kanter for playing time and possibly overtake his starting job if he develops into an elite interior defender. The Celtics will have plenty of scoring in the starting-5, which is projected to include the newly-signed Kemba Walker, Jayson Tatum, Jaylen Brown, and former All-Star Gordon Hayward. Pressed for an impact defender, Williams has an opportunity to seize the starting center duties.