He's not good enough offensively to maximize Cade's abilities. Needs to be more than just a spot up 3 pt threat for them to work in tandem. I don't think it's bad thing to have multiple players that can effectively direct the offense on the floor, but it hurts when one of them is so flawed offensively.
Now on the other end, defensively they have the potential to be ex extremely disruptive, with their length and anticipation. Even as we've had guards ball out against us, a lot of it is the result of them having to over help because of poor rotations and having no real defensive threat in the middle.
I see some potential in Killian in both sides, but he would be best served to be the pg of the bench unit right now as he develops his game. Issue is we don't really have anybody much better to put next to Cade right now, so Killian's getting that spot by default. I would expect to see that change by next season though if we don't see major growth from Killian. This next draft is real important now.