Max's plan before the game was correct. Without proper midfield (he even lost Khedira, who many of us might not like, but he's an important part in Max's logic) and knowing about counter-attacking potential of Atletico, he had to field MDS - Bonucci - Chiellini - AS in defense. Plus it gave him the option of using Cancelo the way he usually uses Cuadrado as a substitution.
In midfield he just fielded everyone he could field. And he tried to shift the balance towards the attack in order to compensate the weakness of the midfield. Hypothetically he could've preferred Bernardesci instead of Dybala, because he's much stronger and punchy, but he probably had his reasons not to do it.
So, I cannot blame him for not being prepared for the game before it started. The problem is, he failed to react to Simeone's moves. And he obviously hoped to keep 0-0 or even 0-1, even when it was clear that the guys cannot stand the pressure anymore and the goals were only the matter of time. It looked like he simply didn't know what to do. Which is very bad.