Kries' philosophy is quite literally "put good players on the field and let them run around." (Part of the reason he has looked like a shitty manager for the last few months - we haven't had any good players.) That's why he likes the diamond, because it's so fluid.
Good players know where to be. They know how to utilize space, they know how to work together offensively, and they know how to position themselves cover defensively.
So talking about "placing" Lampard or Pirlo into a "role" is just not what Kries is going to do. More likely, he places players on the field that will naturally balance themselves out.
Pirlo has played his entire career behind the play as a distributor.
Lampard has played most of his career just outside the box.
Villa has obviously played most of his career way up top, or wide left.
Ok that's three. Looks like we need some defensive cover, someone to make runs, and either another runner or another forward to take focus off Villa. Looks like Jacobson, Mix, and Ballouchy (another runner) or Poku (up top) to me.
Just put those guys on the field and they'll naturally float into their positions. They know what to do.