Count Boston Celtics head coach Brad Stevens as a big believer in incoming rookie forward Grant Williams.

“Grant is who Grant is; a steady guy that impacts winning,” Stevens told NBCSports Boston's A. Sherrod Blakely. “He's one of the few that I think can change his game pretty dramatically and still impact winning.”

The Celtics selected Williams out of the University of Tennessee with the 22nd pick in the first round of the 2019 NBA Draft.

Williams, a 6-foot-7 forward, spent three collegiate years competing for the Volunteers in the SEC before declaring for the draft. The 20-year-old Williams made the All-SEC first team the last two years, winning the conference's Player of the Year in that span, too.

Williams averaged 15.7 points, 6.5 rebounds, and 2.1 assists in 28.9 minutes per game and 104 appearances in three seasons in Knoxville, shooting 51.6% from the floor, 29.1% from beyond the 3-point arc, and 75.8% from the free throw line.

Boston is retooling its team following the departures of All-Stars and free agents point guard Kyrie Irving and big man Al Horford. Irving signed with the Brooklyn Nets in order to team up with friends Kevin Durant and DeAndre Jordan.

Horford will compete for the Philadelphia 76ers, signing a deal worth slightly less than $100 million, to play with Joel Embiid, Ben Simmons, and Tobias Harris.

The Celtics signed three-time All-Star and 29-year-old point guard Kemba Walker to replace Irving.

They also signed big man Enes Kanter, formerly of the New York Knicks and Portland Trail Blazers, and will likely be slotted as the starting center.