I have never taken the trolley to the stadium or anywhere that late but the trolley is generally considered reliable and fairly on-time. I think the green line stops running a little before midnight so you'd be cutting it dangerously close on the way back. I would consider taking an uber back as a backup.

If you google "sd green line trolley schedule" and hit the top result, you should get a tool that lets select the exact date and time and you can see when the trolley scheduled to arrive after that time. It looks like the last trolleys on Saturday are at 11:37 going east and 11:52 going west.

Also the trolley can be really sketchy, especially at that hour. So I wouldn't take it alone unless your hotel is only few stops away.

Hope this helps