You can plow over the other players. Happens all the time to 2B/SS covering second, particularly when the runner is trying to bust up a potential double play. I'd guess far more middle infielders are hurt from collisions from runners than catchers, which makes sense given that they have far less protection. That's a whole bunch of nonsense. Nobody plows into middle infielders. They slide in and occasionaly catch them with their cleats in just the right spot. The injuries are about legs being planted poorly or coming down awkwardly, they aren't getting plowed into, and the lack of protection has nothing to do with how they get hurt.