Report: Walker, Stevens had 'tension-filled' relationship
The two had a "tension-filled" relationship, with Stevens perceived to be harder on Walker than other top players, sources told The Athletic's Jared Weiss.
While Walker and Stevens had mutual respect for one another, they reportedly began to butt heads this past season.
The four-time All-Star was also apparently pissed off by boos from Celtics fans during home games.
Boston acquired Walker from the Charlotte Hornets in a sign-and-trade deal two years ago. He averaged 19.9 points and 4.8 assists while also shooting 37.2% from deep in Beantown.
However, injuries limited Walker to 99 regular-season appearances and kept him out of the Celtics' final two playoff contests this campaign.
Boston traded Walker to the Oklahoma City Thunder on Friday as part of a multi-player deal. The transaction marked Stevens' first move since taking over for Danny Ainge as the Celtics' president of basketball operations.