I'm not worried about Royce as much as you want. Royce is a very good player, and maybe one day will be great. However, he isn't ISU's biggest threat to UConn.
The four guys standing around the 3 point line are much scarier.
I would defend Royce one-on-one all night and stay on the shooters all night. If this means Royce puts up 30+ I'm OK with that, as long as UConn sticks with the three point shooters. Royce dunking in traffic, as long as it's not an "and-one" is much better than having ISU make an open 3 pointer.
I have enough faith that Drummond/Roscoe/Oriakhi will at least bother Royce's forays into the paint.
Even on the dribble hand-off, I would rather give up the occassional free dunk to Royce than an open three for your shooter.