Alaba played most of the time either as a left centerback (with lots of freedom to make runs forward) in a back three with Bernat at left wingback or as a box to box midfielder with Bernat leftback. His future will be in midfield.Forgive my ignorance, I haven't seen Bayern all year, but isn't Alaba your left back?
It's difficult to tell how Guardiola would line up if we didn't have so many injured midfielders though. Maybe Alaba would have played more at leftback if Thiago, Martinez, Schweinsteiger, Lahm didn't miss half the season or more through injuries. Doesn't really matter now that Alaba is out for the rest of the season with another injury .