My suggestion actually goes all the way back to last summer, when I knew we should've resigned TA.
I preferred to have TA over Von, but I'd have given up the spot of Semih, Gody, Avery, Von, Nate, or Marquis to still have TA. Let's assume the ideal scenario, just for fun. Say we had TA instead of Von. At the trade deadline, let's still assume Marquis would've been injured, so I agree with that trade. After that, we should've traded for Anthony Parker. We would've only needed to trade 1 or 2 picks for him. Now, take a look at our roster:
Rondo, Delonte, Nate
Ray, TA, Avery
Pierce, Parker, Gody
KG, Baby, JO
Perk, Shaq, Semih
Avery, Gody, and Semih are inactive. Our 10-man rotation is our starting 5, along with Delonte, TA, Parker, Baby, and Shaq. Nate was slumping, but he's injury insurance for Delonte. JO is injury insurance for Shaq, and if both JO and Shaq are injured, we can put Semih on the active roster.
With this lineup, we have Perk and Shaq in the middle, so there's no need to try to avoid the Magic in the playoffs. We have KG for Bosh. We have Pierce/Parker to defend Lebron. We have TA to defend Wade/Kobe. The chemistry is there, the Celtics understand their identity, and there's a chance we could've had the number 1 seed in the NBA, as well as a healthy roster, going into the playoffs.
Sometimes, you just need to pay up. Ainge let go of TA and Perk and now look at where we are. Hope he learned a lesson after all this.