I'm still trying to figure out how this happened. Part of me thinks there's more here than is being reported. 275 is a lot of weight, but it's not that much weight. Not for a college RB. Heck, it's not a lot of weight for many high school RBs. Anyway, there's only 3 ways that I can think of that this could happen. 1) He's trying to rack it and lets go, 2) it's way too much weight and he lets his wrists roll back and it slips out, or 3) he's literally throwing it up there on the bench and misses a catch.
The first one is the most plausible, but the article says that wasn't it. The second should never, ever happen with a spotter, especially an assistant strength coach. If the wrists roll back, the spotter grabs the bar. That's what he's looking for. As for throwing it up, guys do that in high school and the local gym all the time, but usually not that much weight. They'll throw the weight up as fast as they can, letting the bar leave their hands and catching it on the down. This is very dangerous, and could very likely cause what happened. I'm not saying that is what happened, I'm just wondering if it could be something like that. It's akin to doing push-ups where you push yourself off the ground and clap in the middle, except with a bench press. I've never seen anybody actually try to clap like that doing throw-presses, but I guess it's possible.
Regardless, there's something very odd about that accident. Wish him the best of luck and a speedy recovery. I can't imagine how much that would hurt.