I think Max would have gone four at the back anyway, though with Chiello and Bonucci.
The disappointing thing about this is, it takes away our option of going 3-5-2 to see the game out. During last year's Champions League run you'd see Barzagli warming up and it was basically Allegri saying "there shall be no more goals today".
I was expecting a back-four, but Barzagli to come on if we were up 1-0 or something with 10-15 mins to go.
I really, really rate Rugani but I think it'd be unfair on him to expect him to come on and shore up a game against one of the best teams in Europe at this stage in his career.