Johnny Cueto wasn't in the best fielding position when he released his pitch, but was able to get enough of his head out of the way to avoid serious injury. The ball appeared to glance off of his forehead before travelling into right center for a double.
Cueto wasn't injured and was able to stay in the game. I'm sure the wings will be out and there will be people fluttering around talking about helmets for pitchers.
Helmets aren't the answer. To reduce these types of situations pitchers need to be ready to field the ball after they throw a pitch. It isn't all that hard to do. It's called using proper mechanics.
You have to be ready to field the ball when you're on the mound.