It's much more than that. His on court/off court numbers are among the worst on the entire team. The team gains about 1 pt per 100 possessions when he's the floor, but gives up about 6 points more defensively. His 2Pt FG% is good, but it's not so elite as to justify his not shooting threes. This season, players like Gordon Hayward, Joe Harris, Seth Curry, Donte DiVencenzo, & TJ Warren had better 2pt%s, and they all also shot the three, giving them all better adjusted FG%s than DeRozan. Among SFs, he ranks 51st in the league in RPM, behind guys like Cedi Osman and Andrew Wiggins. If you classify him as a PF, he'd rank 49th. If you classify him as a SG, he'd rank 77th, behind Grayson Allen and.... wait for it..... Bryn Forbes. Anyway you look at it, DeRozan is making superstar money but producing like a very average player. And none of this is new. These issues of net production have plagued him for a decade, and are much worse in the playoffs.
http://www.82games.com/1920/19SAS9.HTM
https://www.teamrankings.com/nba/pla...oal-percentage
http://www.espn.com/nba/statistics/rpm/_/position/5