While it may be a natural reflex to compare a current to a past coach, Tubby's firing and Pitino's hiring were two different events. Tubby's firing created an opening for "a" coach, not necessarily "this" coach, so being dissatisfied with Tubby does not indicate that one must be satisfied with Pitino. It's not like breaking up with one person for the purpose of dating a specific other person.
Of course they are two different events. But one event (Tubby's firing) had to happen before the other event (Pitino hiring) could. If Tubby lasts another year or two or another year less do we still have Pitino? I doubt it, it's not like Pitino was just waiting around until Minnesota had the opening.