I think there's a good chance Irving does a Paul George and stays with the Celtics. Assuming Butler goes to the Clippers (along with Kawhi Leonard) and Durant and Thompson stay with the Warriors or go to the Lakers, what would you do?
We could either keep the cap space and just continue to develop young players and draft (maybe take on salary for a pick), or we could max out a second tier player.
Personally I'd be tempted to go for Middleton, he isn't flashy but he's a good defender and pretty good on offense. He can play SG and SF, allowing for a lot of versatility (Knox can play SF and PF, KP can play C and PF).
Other second tier players are: Kemba Walker, Cousins (NO!), Horford (too old), Tobias Harris, Bledsoe (no), DeAndre jordon (too old), Harrison Barnes.
For me there's a real chance we miss out on the top players, so it reinforces my belief we shouldn't stretch Noah until we know we need and can fill the space.