How about a trade for Devon booker or D'Angelo Russell?
Fultz/Ball or Booker ,Russell who has the highest ceiling?
Booker/Russell are both more ready to contribute to a playoff team IMO. They are both still on rookie contracts I believe, allowing us to still possibly land a max free agent as well.
The short answer is that this is the difference between fantasy sports and reality. It would make sense to trade for those guys in a fantasy league. In reality, it would be disastrous.
The longer version of this is to actually analyze it. Let's do that now.
Let's take out the easy one. Russell? Fultz' low water mark would be Russell. Russell may be better now but Fultz should quickly surpass him. This isn't a deal I'd even consider unless LA sent back their 1st rounder this year (which they probably can't).
Booker? Okay, let's actually consider that one. We know Booker can score even despite the refs not allowing anyone to play defense on him in that game (26 free throws were absurd). The guy did average 22 ppg this year but on a bad Phoenix team meaning some of those are empty stats. But let's just say he's the more attractive target (which I'm not convinced of - I think Fultz has a significantly higher ceiling).
But here's the problem with both guys - they're going to be coming off the bench. Neither can play with IT because they're massive defensive liabilities. That would literally be one of the worst defensive back courts in recent NBA history. And I don't think we can stick IT on the bench after putting up 29ppg this year. A IT/Booker backcourt would make the Lillard/McCollum backcourt look like it was comprised of Avery Bradley and Dennis Johnson.
In short, they don't fit the needs of the Celtics even if they're better today.
A guy like Fultz is going to come off the bench this coming year and physically has the tools to be a better defender than either of those guys. Thus given his game and the expectations of any draftee, he's a much better fit for the team long term. He can learn the game the right way for a year and then take over a starting spot in 2018 with 3 years left on his deal.
Finally, another consideration is the cap space. With both of those guys eligible for RFA in two years, it seems like a waste to trade for one to make them come off the bench. Furthermore, the timing of expiring contracts doesn't work as well. Al has 3 more years. Brown is eligible for RFA in 3 years. That's not really a coincidence. If the Cs choose to resign Bradley, IT or a UFA it will likely be for 4 years so that our 2017 draftee is eligible for renewal the same year that larger contract is expiring. Moving that up two years could add complications to the cap situation.