Headhunting, knockdowns, chin music, brushbacks, rib-roasting -- the practice has been around so long, there are all sorts of terms for it. In the 21st century, there is only word we need: unacceptable.
The practice of intentionally firing an object 97 miles per hour in the direction of another human being has got to stop. It's incredible that it still happens. In the real world, we've got a word for such behavior: assault. In the baseball world, it's a practice that lingers for no better reason than it's something that has always been around.
In some ways, you can't entirely blame hard-throwing Marlins righty Jose Urena.