Actually, if Perk doesn't get injured, I think we get a sequence like:
Ainge: What will it cost to sign you? We can only give you this much for an extension, but if you promise not to negotiate with other teams, we can agree to a contract that we will sign you to using your Bird rights. Well, unless the CBA changes everything and we get a hard cap.
Perk: I want to test the market to establish my value, but I'll give you a chance to match.
*Ainge consults his rolodex, seeking to trade Perkins*
Ainge ends up trading Perkins to OKC for Jeff Green (who he has always wanted...and Ainge tends to be mentally locked onto players for several years) and the rights to Cole Aldrich. He still uses the Celtics' own first-round pick on the guy he coveted all along, Avery Bradley. Since Green can play power forward, Ainge doesn't draft Harangody in the second round. He considers Willie Warren, Sylvan Landesberg, Derrick Caracter, but decides he wants a mature guard taller than Avery Bradley, preferably one who played four years of college, who has a chance of contributing immediately as a 10th or 11th man. He ends up drafting someone like Gonzaga's Matt Bouldin, Duke's Jon Sheyer, Harvard's Jeremy Lin
With Green as the back-up three, Ainge and Marquis Daniels decide to see other people. Ainge does, however, bring back Nate Robinson. Ainge still uses the MLE on Jermaine O'Neal, with Shaq successfully lobbying for a spot on the roster. Having Aldrich to develop, Ainge lets Erden stay in Turkey.
This gives the Celtics a roster of Rondo, KG, PP, RA, O'Neal, O'Neal, Glen Davis, Green, Aldrich, Bradley, second-round guard, NateRob. The Celtics still pick up Von Wafer and Delonte West, as Ainge wants some experienced players ahead of his two rookie guards. Deciding that another big is more important than having someone other than Von Wafer as the third-string small forward, Ainge picks Chris Johnson over Stephane Lasme, Tiny Gallon, and Mario West as the winner of the final roster spot.
With a couple of banged up O'Neals, a guard gets waived as soon as a viable experienced big that Ainge likes appears on the market.