Quick Thoughts On Aroldis Chapman (With Mariner Tie-In!)

by Jeff Sullivan on Aug 31, 2010 2:58 PM PDT in Miscellaneous

The Reds have promoted Aroldis Chapman to the Major League bullpen today, the timing of which allows him to be playoff-eligible. Chapman has generated considerable buzz of late after he was clocked throwing a 105mph fastball in AAA. This, of course, is an eye-popping number, roughly twice as fast as Jamie Moyer throws, and thrice as fast as Jamie Moyer drives.

I will take this opportunity, then, to mention once more that what matters isn't actual velocity. What matters is perceived velocity. Actual velocity is by far the biggest component in perceived velocity, and I'm not saying that Chapman has some sort of perceived velocity shortcoming. It's just that his being around is going to make a lot of people start talking about fastball speed, and a lot of those people are going to be kind of missing the point.

Let's say that Aroldis Chapman hovers around a 100mph fastball in relief. That 100 can look way different to a hitter depending on where it's located. Sometimes a 100mph fastball will look 90, and sometimes it will look 110. By the same token, sometimes a 90mph fastball will look 80, and sometimes it will look 100. Aroldis Chapman throws really really hard, but more important is whether hittters see that, or if they see something less.

There's no doubt in my mind that hitters don't exactly stand in against Chapman with glee. This is more of a general point than a specific one. Keep perceived velocity in mind. Consider whether a guy is tall or short. Consider whether he pitches up and in or down and away. A high or low reading on the radar gun is only a start.

When you hear about something like a 105mph fastball, your assumption is that the guy is untouchable. This is where the numbers come in handy. Chapman's numbers as a reliever in AAA are outstanding. He's whiffed 49 and walked 12 over 30 innings, with 55% groundballs. His numbers are not, however, unheard of. Of the 802 pitchers in AAA who have thrown at least 100 pitches, Chapman's 12.6% swinging strike rate ranks 82nd, behind names like Luis Perdomo and Mitch Stetter. Hitters have not had as much trouble putting bat on ball as you might think based on velocity alone. That Chapman throws really hard is important. That Chapman hasn't exactly generated league-leading pitch results is also important.

Chapman's contact rate in AAA is worse than those of Clay Hensley and Tyler Clippard in the bigs.

Despite that caution, the probability remains that Aroldis Chapman will be terrific, if something short of mythical. And so I present to you the following AAA numbers:

Aroldis Chapman: 71.1% contact as a reliever, 76.9% contact as a starter
Josh Lueke: 73.6% contact as a reliever
Mauricio Robles: 73.3% contact as a starter
Michael Pineda: 72.8% contact as a starter

Chapman's going to strike a lot of guys out. So are a few future Mariners.