I think that if the team was to play without Mandzu, it would be a lot harder to put the same amount of pressure on their backline (regarding crosses and headers in the box at least). I don't know how Atletico set their defense up, but it appeared to me that Godin was on Mandzu most of the time - and even if Mario had a bad performance it definitelly freed up Ronaldo. It's also reasonable to say that this might have been Allegri's plan.
Imo, if Dybala played instead of Mandzu, Godin would 100% be on Ronaldo the whole time (unless he goes wide). Also regarding just physical presence and aerial threat in the box, Kean comes no where near Mandzu. From what we've seen from Kean so far, I think he'd be great against teams that put pressure and play attacking football. He'd be great at disrupting midfields, counter attacks and creating chances for himself by overruning one or two defenders - very explosive and strong on the run.