It seems that sometimes you have to move a guy to your active roster to get his usage updated.

Perhaps you overused him early, sat him on the bench waiting for his usage to drop, and it never did.

Activate him before stats are updated and see if when stats are updated his usage isn't also.

I "think" you may have to do this prior to when stats are updated or it won't happen until after the first game is played.

...and maybe I'm all wet.