He took an elbow to where his kneck and shoulder meet on his shooting arm and you could see the trainers working that area on the sideline several minutes later, suggesting his shoulder muscle was tightening up. Knell also went 0-2 from the 3 point line and played the least minutes of any starter.
Those types of minor nicks and bruises just happen in a physical game like this even when players aren't doing anything wrong, but it's not a basketball play to fight through a screen by throwing an elbow to the neck of the person setting the screen. That play essentially eliminated one of our best offensive weapons from the 3 point line through a flagrant foul/cheap shot.