Here is a picture of someone I knows arm right after surgery from a broken wrist from pole vaulting. He actually really did not do all that much wrong when it happened, so it goes to show that sometimes freak accidents just happen. He is a well coached vaulter that was landing deep in warm ups, and on his first jump he just didn't quite go in far enough and came down and landed on his feet in the metal box, and he fell backwards and put his hand down behind him to catch himself and landed on his wrist wrong.
But had he had better awareness of where he was in the air and just road the pole back to the ground this could have been avoided...