Given his history with the C's, "a**hole" (read: true competitor) mentality, and considerable pure point guard skills, I'd love to see Rondo back in Green if he can get all of his explosiveness back and/or build on the jump shot development we've seen from him in recent years. If those things can happen, I think he'd be deserving of a max contract from us, although it would obviously help things if we could eventually figure out how to get him the help he needs to go deep into the playoffs (ie elite offensive help/rim protecting center).
Out of curiosity, what sort of stats would you need to see from Rondo for you to consider him to have re-established his value?