There isn't "training blocks", the team generally trains together everyday. In this particular case the thrower isn't even on the team anymore, he was training post collegiate, and throwing from the discus cage. No doors, more like a backstop for softball. I wish there were blocks of time set aside for certain events, "especially when training post collegiate" but we don't operate that way. I'll agree that the thrower shared responsibility, but the bulk has to fall on the coaches shoulders. The coach made a poor decision, ignored everyone else's safety and someone was hurt bad.
The good news is that it looks like he's not going to be paralyzed. It broke some vertebrae but the cord seems to be O.K. He's still got a long road to recovery, broke ribs, scapula and a punctured lung etc... What's it going to take before those big cages are mandatory? Someone dying?