Back in the good ole' days...
As middle infielders, we were taught to throw at a baserunner's head coming into second base.
We were also taught to jump and get out of the way after making a strong throw to first.
99% of the time, the runner ducks down because he doesn't want a ball in the face and knows it's coming.
I have many scars on my shins and knees because of aggressive baserunners. However, I don't mind them because that's how the game of baseball is supposed to be played...