I am not trading Fultz and Bradley for Klay.
I am not trading IT, Nets '18 (potential top-5 pick), KO, and Jae for a year of PG13.
If I'm Danny Ainge, I look to add pieces now to make us better (Hayward, rebounder, etc.), while also building the future. We are undoubtedly a top-5 team right now. Where within those five remains to be seen. Just adding a talent like Fultz to the bench is big. Add a rebounder (one with experience and/or Zizic) makes us even more dangerous. If we can land a star to bolster our starting unit, we will have no holes.
I'll take a 60-win team next year with Rozier, Smart, Brown, Fultz, Zizic all 23 or younger.