Lonnie Walker IV signs with Celtics, filling final roster spot on ...

BOSTON -- The Boston Celtics have filled their final roster spot, reportedly signing guard Lonnie Walker IV on Wednesday night. 

Brad Stevens continues to cook in the front office for the defending champs, as Walker was arguably the best free agent left on the market. There's no guarantee Walker will make the team, as he's reportedly signed an Exhibit 10 contract -- a non-guaranteed deal that is essentially just a training camp invite.

But getting a player like Walker to fill the 15th spot on the roster is an embarrassment of riches for the Celtics. The 25-year-old averaged 9.7 points over 58 games for the Brooklyn Nets last season, when he knocked down 38.4 percent of his shots from downtown. A first-round pick by the Spurs in 2018 out of Miami, he played four seasons with San Antonio and the 2022-23 season for the Los Angeles Lakers.

For his career, Walker has averaged 9.8 points per game off 42.2 percent shooting overall and 35.6 percent from 3-point range. Should he make the team, he could earn some important bench minutes thanks to his 3-point shooting and athleticism. His signing essentially closes the door on a return for Oshae Brissett, who remains unsigned.

Brissett and Svi Mykhailuk (who signed with the Utah Jazz) will likely be the only members of the defending champion Celtics who will not be returning next season. Walker is the only free-agent signing by the Celtics this offseason, as Stevens made sure to bring back nearly everyone from last year's championship squad.

More from CBS News