If you're looking for what happens if a pitcher throws a baseball close to the speed of light, XKCD has you covered with this article, which includes the following passage:
↵It hits the bat first, but then the batter, plate, and catcher are all scooped up and carried backward through the backstop as they disintegrate.↵
But if you're looking for why you're reading this in the first place, XKCD has you covered here. It's always fantastic when my nerd worlds collide.