If there's no structural damage and he has the possibility of playing this weekend I find it highly unlikely that he dislocated his shoulder. To posteriorly dislocate your shoulder there either has to be structural damage or severe posterior/multidirectional instability. With the later, it would have already been an ongoing problem for him. Either way, it's not an injury that will just get better or be good enough to go in a week. My guess is that this was a false report and it was some other shoulder injury less severe.
(Disclosure: I'm an orthopedic radiologist)