Wrong. He's a better, more willing and still improving 3-point shooter, with some off the dribble ability.
The pressure he initially had with the Magic wouldn't exist here. It'd be akin to Iguodala being miscast as the 76ers post Iverson "savior" before converting to his ideal swiss army knife role with the Nuggets and Warriors.
Spurs don't need DeRozan's inefficient garbage and the rotational gymnastics required with him. Redistributing those possessions through a myriad of options (mainly the 3 young guards), while improving defensively, would make them better overall.