I think the motive for Allegri is to have Sturaro doubling on Ronaldo. Maybe using up a yellow in the 1st half. There is no risk for us if Sturaro batters Ronaldo. If he's getting close to a red we can always sub him.
I think we want to keep Vidal free from defending so deep beside Lichtsteiner. We want to use him to roam the centre of the pitch. Normally he can do that from CM but with Ronaldo on the pitch I think Allegri wants that CM spot to be shadowing Ronaldo.