We need a big man, but TT can't guard the people we need guarded. He might do a decent job on a true center like Embiid, but he does nothing for us in trying to cover Greek Freak or Siakham. Jaylen is the best matchup we have for those guys, and it's doubtful we can trade for a better option. Brad isn't going to play many 2 big lineups, maybe when Grant Williams is out there, so I think any trade for a big is farfetched, obviously, except if incredible value becomes available.
The guy we're searching for probably isn't feasibly obtainable. IMO, the move I'd want the Celts to make would be to re-acquire Baynes once the Suns' season falls apart.