Vidal is not a normal player. I acknowledge his form has dipped, it's obvious. But there are some players that earn the right to play the big matches because they have delivered in the past. No one would be surprised if Vidal popped up with a brace tomorrow.
I agree in a sense that Pereyra is better suited as an AM but on the other hand, Vidal's finishing is far superior to Pereyra and IMO is possibly top 3 on this team. I guess it comes down to how important you think form is when dealing with world class players.
I have nothing against Vidal playing. I do think he should stay on the bench since Pirlo, Marchisio, Pogba and Pereyra are all in better form but I'll be fine if he plays but as b2b. If Allegri wants to fit Vidal in he should move Pogba to AM role imo.
I completely agree he's a very good finisher, superior to Pereyra definitely but Pereyra has different qualities Vidal doesn't have. Pereyra is a very direct player, he's comfortable dropping to wings, has a decent through pass and crossing. He can beat his man and create advantage for us. He's a very good link between midfield and attack. He offers us ability to counter attack as well. Pereyra isn't as good as Vidal at defending but that's just another reason to play Pereyra as AM and Vidal as b2b.
Again it's not a problem for me Vidal would play, it'd be ridiculous. I think without form Vidal played out of position is not what we need in this match though. If we want Vidal to play AM then we should play Morata instead of Llorente. With Pereyra out and Vidal in we're losing dynamism IMO. That's why I'd see Morata near Tevez since both can counter attack and make runs behind defense. Otherwise it'll be too static.