It all depends on contract length. I'd be more willing to give Green bigger and longer money since he has more upside than Baby. However, in the case of all of the players (though especially Baby and Krstic) I'd like to see management overpay them on 1-2 year deals. For instance, if Baby gets a 3 year 15 million dollar offer elsewhere, would he take 7-8 million for one year here?
Now that's easier said than done with the luxury tax; however, it's something that could payoff big time next year (for one last run) and in the long term (with cap space).
Though to play devil's advocate to myself, with Shaq and JO under contract next year and the possiblity that Krstic is back, plus the possibility that they could sign a vet center to a MLE deal, do they even want to bother to commit any money to Baby? If the C's are serious about giving Green big minutes, he's likely going to need all the backup minutes behind Pierce AND Garnett. And that'd leave only the 5 spot for Baby, and if that's full too, it wouldn't make a ton of sense to break the bank for him.