Manu being a Gamer has nothing to do with his bad back. And maybe thats why the spurs don't mind having a glut of guards, because they anticipate Manu not playing more than 3/4s of the season.
This will also present an opprotunity for De Colo to show if he's legit or not. Remove Manu for a week and let's see if De Colo and Neal can play well as the off guard. I hope Mills is the unquestioned back up PG, since he's the 2nd best ball handler on the team. With Manu out, this early, let's see what depth this bench has.