Villa gets gobbled up when alone on top. We need some muscle up there to hold up play and take some focus off him. I think by August, when Mix and Pirlo are both in the lineup, our heatmaps will look like a 4-2-2-2:
I'm abandoning my usual clean format to show a few things.
Up top, Villa tends to drift high and left, while the second striker drifts more centrally to receive long balls and passes from the midfield.
Centrally, Mix has the legs to make runs forward, but will also need to cover defensively as Lampard and Pirlo will be relatively stationary, with the former in the middle of the attack making secondary runs into the box, and the latter trailing behind the play and making the initial distributions.
The fullbacks play very high, because we absolutely need them for width in this formation, and they have attacking tendencies anyway. I wouldn't be surprised if they show up on heatmaps higher than Pirlo as well some games. So I have them in line with Jacobson here, who usually plays like a 3rd CB already. (And we need him there. Against NYRB, he played higher up the pitch than he ever has this season, and our defense got absolutely torched. Check here:
http://www.whoscored.com/Matches/914956/MatchReport)
I was hoping a 4-1-4-1 or 4-2-3-1 would work to give us some more midfield legs, but Villa just looks so dull up there alone. If you just threw our roster on the field with no instruction, I think they would naturally play in the 4-2-2-2 I diagrammed above, which is likely our only viable format for the next year and a half.