Nobody was in a position to take a shot until the guy for Nebraska actually took the shot. Easily could've fouled. The main problem was Koenig played horrible defense on the last possession. When they set the screen, Happ came out to the guard to contest as he's heading towards the corner. That's going to be an incredibly difficult shot to make with a guy 8 inches taller than you defending knowing that you have to shoot the 3. So Happ basically has the guard, there's no reason for Koenig to rush over to recover on defense. The only thing he needs to do is either guard the guy who set the screen or get himself between the ball and the screener to make the pass back to the screener a lot more difficult, if not impossible. Instead he flies back to the guard at a bad angle, over commits on defense and ends up running past the player with the ball. This allows the guard to make an easy kick out pass to the screener who is now wide open because Koenig decided to switch back on defense even though there was no reason to.