Maybe it's bad mechanics. It seems like every hard throwing pitcher is treated like glass these days. Throwing hard and learning how to pitch seem distant. Mark B. never had a fastball that could blow by hitters but he knew how to get people out.
It's nice to see a 98mph fastball on a radar gun but if there is nothing on it there are plenty of ML hitters who make it leave just as quick. You can get away with it on the minors but in the big leagues you are facing guys who make enough money to have their bats custom made.