Can Poku play the slot you've earmarked for Calle? I could also see McNamara in there for Poku's CAM/CF spot. Otherwise I could see this, say early August. My only worry besides defense and can Pirlos and Lamps legs handle it, is will Tommy McN support Villa up top by his lonesome?
Honestly I like Poku best off the bench, coming in to dribble at tired defenders. I don't think his game is well rounded enough to play off of Pirlo yet. Positioning is going to be key for all of our starters (knowing where they need to be at all times and learning to think like Pirlo), and that's one of Poku's weak spots I believe. If Poku does start in this formation, I think he's better up top where his physicality can really take some focus off the smaller Villa.
I'd play Calle or Ballouchy as the other mid. Calle brings more defensively and physically, so I penciled him in. I seem to trust him more despite seeing less of him, merely because I've seen more of everyone else and I already know they suck.