It's a great question, isn't it?
Better NBA shooter than Jimmer, more NBA ready, more of an NBA body athletically, great size for a SG who can still hang with some SF's, and was available. And as we saw with the game on the line can get a great look 1v1 which he just happened to missed yesterday. Even if we didn't use him as a SG and a SF instead, how much better would we look with IT/Reke/Klay out there? We needed spacing and there it was. Or running Reke at point with MT/Klay spreading the floor. Reke would have much more room to attack and they'd be getting great looks off his penetration.
Oh, what could have been.