In retrospect, Patty Mills should've probably taken more time to rehab from shoulder surgery last season and not rushed back into action. He says he's back in 2014 form now.
The Spurs, like many NBA teams, hold "open gyms" in their practice facility over the off-season so that players can work out and scrimmage against each other in informal games. Coaches love the idea for many reasons. It keeps their guys in shape, helps form chemistry between current players and newcomers. Perhaps most importantly, they know the floors in their gyms are safer and better maintained than some outdoor concrete blacktop somewhere, and more private for the players too, which is vital in this day and age.