Hitting is hard enough, and it gets even harder when guys are really on. But there aren't a lot of guys who throw like that. San Francisco Giants closer Robb Nen finished first in a poll of more than 20 major league players, which isn't surprising considering Nen's fastball regularly reaches 100 mph. Armando Benitez of the Baltimore Orioles, Mariano Rivera of the New York Yankees and Mark Wohlers of the Atlanta Braves were also listed frequently. He definitely throws hard, and a guy with an arm like his is probably only going to get better as he continues to learn how to pitch.
Some hitters actually prefer to face the heat.
You get in a rhythm facing those guys, because you see them more often. If you've got a quick bat, you can sometimes catch up to guys who throw that hard. And a lot of guys who throw hard, and throw their fastballs for strikes, are very proud of that. They'll throw their fastballs in any situation. You can use that to your advantage as a hitter if you're prepared, and you have the bat speed to capitalize.