Part of the reason is that Gay, while he has the ability to create his own shot, is also inefficient offensively. With Memphis, Gay had a paltry effective field-goal percentage of .438, and that has fallen to .406 with Toronto. His true shooting percentage was a diminutive .478.
Sometimes that can be forgiven if, in the process of taking those shots, a player also opens up looks for his teammates and shares the ball. However Gays 12.1 percent assist rate, along with the fact that his teammates shot better when he sat on the bench, indicate that Gay wasnt doing that.
Throw in that he had a usage percentage of 25.5, and you come to the conclusion that he was perilous to Memphiss offense.
Inefficient scoring on a quarter of the teams plays while on the court, coupled with ball-hoggery, is a dangerous combination. It means Memphis was effectively wasting a lot of possessions.