What I'm saying is that Ale and Borriello have extremely different characteristics, and Conte selects players based upon the characteristics that he thinks will best impact specific matches. Tactical theory, man.
The two don't have the same role when they're on the pitch.
If it was my choice, Ale would never sit behind Borriello - never. Personally, I believe ADP's quality is so far beyond Borriello's, that it's a damn travesty when that happens - especially because Ale's skill set allows him to hold the ball up as well as Marco, while also offering the Del Piero magic that we're all so familiar with.