Interesting thing about the Cornbrook derailment was that when that happened Bury-Altrincham trams were already only using the Exchange Square route because of the track works between Piccadilly Gardens and St Peter's Square. Obviously they couldn't use either route through Manchester once the derailment happened so all trams from Bury were diverted to the Etihad Campus via Market St.
Clearly they were being turned round at the Etihad quickly, so why can't they do this on match days? I've suggested this before that instead of trams terminating at Piccadilly, run them through to the Etihad for an hour before and after games. We know they can do it now.