Regardless of what Ainge did it would have been nearly impossible to duplicate last season's success. We were lucky with injuries and lots of things went our way. Our team is not built to survive a truly major injury, and nothing Ainge could have done would have fixed that. PJ Brown had one good game but was pretty bad besides that, and Cassell was more often a minus than a plus. So we really only lost Posey, but TA, BBD and Powe should all be better next season as they gain more experience, practice, conditioning and health.
-Starters are the same, but with more time together and playoff experience; Perk and Rondo are also still on the upslope of their careers.
-6th man, instead of Posey, is now determined by who needs to come out first: House or Tony can enter if Ray or Rondo sit, Tony can enter if Ray or Pierce leaves, and Powe enters first if KG or Perk sits.
-Regardless, our first 4 off the bench are House, Tony, Powe, Baby; Baby, Tony and Powe should be ready to do more than they did last season in terms of minutes and contribution. Scal, for all his shortcomings, knows his limits and plays good team D. That's 10.
-Therefore, the question marks are really only players 11-15: Giddens, O'bryant, Walker, Pruitt, Miles. No doubt one of those will be cut if a great midseason buyout happens. In that part of the bench I have no problems messing with projects/gambles, since, as I said above, our roster is far too top heavy to address potential major injury insurance via MLE free agency.
In conclusion, we probably won't win a title, but nothing Ainge could have done in free agency - not even bringing back Posey at any cost - would have guaranteed a title. Ainge could have done better, possibly, but the potential upgrades discussed probably wouldn't have affected actual games that much; most of the team is returning intact.