Brian Windhorst is skeptical the Celtics can replace Kyrie Irving and Al Horford in free agency, and the Get Up panel feels Boston's window to win quickly closed. (1:51)

The Boston Celtics agreed to trade center Aron Baynes and the No. 24 pick in Thursday night's NBA draft to the Phoenix Suns for their 2020 first-round pick (via the Milwaukee Bucks), sources told ESPN's Adrian Wojnarowski.

The Suns used the 24th pick to select Virginia shooting guard Ty Jerome.

Boston had acquired the Nos. 24 and 33 picks from the Philadelphia 76ers for the Celtics' 20th pick earlier Thursday, the teams announced. Philadelphia used the No. 20 pick to select Washington small forward Matisse Thybulle. The Celtics used the No. 33 pick on Purdue guard Carsen Edwards.

Baynes, a seven-year veteran, was plagued by injuries in the 2018-19 season, averaging 5.6 points and 3.0 rebounds in 51 games.

The Celtics had been offering Baynes -- with his $5.4 million expiring contract -- so they could clear salary-cap space, league sources told ESPN. Without Kyrie Irving and Al Horford on the books, Boston is now sitting at $25.8 million in room under the cap after the trade with Phoenix. That could increase to $34 million without guard Terry Rozier, who is a restricted free agent.

After acquiring Baynes and the rights to Jerome, the Suns now have a projected $14 million in cap space.

The Milwaukee pick going to Boston via the Suns is protected for picks Nos. 1-7 in 2020 and becomes an unprotected first-rounder in 2021 if not conveyed. That means Boston now has the potential to have three first-round picks in 2020.

Earlier Thursday, the Celtics selected Indiana's Romeo Langford with the 14th pick. A 6-foot-6 guard, Langford played through a thumb injury and finished sixth nationally in freshman scoring in his lone season with the Hoosiers, averaging 16.5 points.

Langford is the third wing player Boston has selected in the first round in the past four drafts.

Langford said he hasn't had a chance to watch many NBA games recently because he didn't have cable in college.

But Celtics coach Brad Stevens called him "a guy that we think has a lot of things that can translate to the NBA."

The Celtics also picked Grant Williams out of Tennessee with the 22nd pick. Stevens said Williams, who averaged 18.8 points and 7.5 rebounds as a junior, plays with a point guard's mind.

"You can run offense through him," Stevens said. "He thinks the game. He's a tough, tough guy, and he's a versatile player who can shoot the ball."

Boston also took LSU point guard Tremont Waters with the 51st pick.

The Associated Press contributed to this report.