I mean, best case is he returns and becomes the second best big in the East (unless you include Giannis as a big-man). 
I literally have no idea what the worst case is. He's never seemed to actually clash with teammates, which is good. I dunno, at this stage go for it, lol. 
If DeMarcus returned to 25/12 and Gordy returned to Utah this team is a really big problem though! Fantasy, but who cares, that's the fun!