Here's a Thought: Are the Scouts Wrong About Vince Mazzaro's Curveball?

Nathaniel StoltzSenior Analyst IJuly 24, 2009

OAKLAND, CA - JUNE 28:  Vin Mazzaro #54 of the Oakland Athletics pitches against the Colorado Rockies at the Oakland Coliseum on June 28, 2009 in Oakland, California.  (Photo by Ezra Shaw/Getty Images)

"Mazzaro is still trying to find a reliable offspeed pitch. He didn't throw his changeup much last season, though it took a step forward and could become an average offering. His curve is more of a show-me pitch."

-Baseball America Prospect Handbook 2009, on Vince Mazzaro's changeup and curveball

Baseball has scouts for a reason. They spend their lives identifying and classifying talent of hundreds of baseball players.

Sure, sometimes scouts disagree on a certain player's potential, but there's usually some sort of "scouting consensus" on most players and their attributes.

One great source of the "scouting consensus" is the Baseball America Prospect Handbook series. The handbook ranks the top 30 prospects in each organization, and gives a nice two to four paragraph breakdown of their strengths and weaknesses.

The handbook helps me out a lot when I'm looking to find out what a pitcher throws, so I can understand what pitches are producing his numbers.

Naturally, I tend to look at the A's more intensely than any other team, although I do read the whole book every year.

Coming into the year, I noticed that Vince Mazzaro, currently in the A's rotation, was said to have a very good sinker and an average slider, to go with the less-than-glowing descriptions of his changeup and curveball that are quoted to begin this article.

If you don't know what a "show-me pitch" is, it basically means "He throws it just to give hitters one other pitch to worry about, but it isn't very good at all."

So Mazzaro sounded like a nice sinker-slider third starter with a below-average changeup and a curveball he'd toss in once in a while.

Now, Mazzaro has made nine starts for the A's, and has been a decent fourth starter.

Looking at his pitch type breakdown, Mazzaro throws his sinking fastball, which averages 92.7 mph, 63.1 percent of the time. He works in the so-called average slider (85.2 mph) 22.8 percent of the time as well. As the scouting report says, he tosses his 85-mph changeup infrequently (7.5%) and uses the 80.8 mph curveball even less often (6.7%).

Now that makes sense: Mazzaro leans heavily on his two best pitches, only occasionally working in the iffy changeup and curveball.

What doesn't make sense (to a certain extent, anyway) are the results he's getting. Consider the following:

Pitch      Runs Above Average/100 Pitches
Sinker     -.90
Slider     1.31
Change   -.08
Curve     3.37

Mazzaro's curveball has been his best pitch. It's been the best curve on the A's and one of the best in the major leagues, at least in terms of the results it's getting.

The sinker has been his worst pitch.

Hey, at least the slider's better than the change, right?

The scouting reports seem to indicate that it should look something more like this:

Pitch      Runs Above Average/100 Pitches
Sinker     1.00
Slider     0
Change   -.6
Curve     -1.5

Now, those are just arbitrary values I'm throwing out there, but a "plus" pitch roughly translates to a run above average, an "average" one is zero, a "below-average" one is in the -.5 to -1 range, and a "show" pitch is even worse.

Obviously, the scouting reports are overrating the sinker and underrating Mazzaro's other three pitches, right?

Or is there another explanation?

Well, there's an easy explanation for the sinker's "ineffectiveness."

Batters read the scouting reports that say Mazzaro's only plus pitch is the sinker. They watch film of Mazzaro throwing a ton of sinkers. They go up there ready to hit that sinker.

And hey, they're big-league hitters. They look for the sinker, Mazzaro throws a lot of them, they see what they're looking for, and they hit it, whether it's got good velocity and movement like Mazzaro's or not.

For much the same reason, Joel Zumaya's fastball, for example, rates below-average. Even in his best days, Barry Zito didn't get overwhelming results from his curveball, because hitters were always looking for it. Zito got better results from his fastball and changeup.

So Mazzaro's sinker getting hit around a bit is understandable.

In much the same way, the success of Mazzaro's slider and change is understandable. Hitters are too worried about the sinker to think about the slider or the changeup, so both pitches play up, with the slider becoming a plus pitch and the changeup becoming average.

In that same vein, it's reasonable to expect Mazzaro's curveball to step forward and become at least a passable pitch, because hitters certainly aren't looking for it.

However, it's one thing to outperform very low expectations, and quite another to excel to the degree Mazzaro's curveball has.

There's no obvious reason (that you can see on a data sheet) that the curve would have more success than the changeup. It's thrown about as often (so hitters see it as often), and scouts rate it lower. If the changeup is essentially average, one would expect the curve to be a bit below average.

Looking at the pitch itself, it comes in at 77-85 mph, which is pretty hard for a curveball, but it's also easily the slowest pitch of the four Mazzaro throws. The average curveball breaks 5.3 inches horizontally and vertically, but Mazzaro's just has 3.4 inches of horizontal break and 1.6 of vertical.

So, in terms of movement, the pitch backs up the scouts: It doesn't move anywhere near as much as most curves, so it doesn't rate highly.

What it does do is break quite differently from Mazzaro's slider, which has 1.9 inches of horizontal break and 2.0 inches of vertical "rise" relative to a ball with no spin.

I thought maybe both breaking balls had the same spin, making the curve harder to pick up, but Pitch F/X data shows the two breaking balls to have different spin directions.

With no obvious statistical explanation for the success of Mazzaro's short-breaking curveball, I had no choice but to go look at the pitch. Yes, I've seen Mazzaro pitch several times before, but it's not like I went into every start hell-bent on understanding what his fourth-best pitch does.

So I looked at the data, found a bunch of times when he threw the pitch, and took a look at it (Rock on, MLB.TV!).

Mazzaro likes to throw the curveball down and away, which is the tough spot to hit pitches. It doesn't have big, Zito-esque break, but what break it does have comes very late and catches hitters off guard because they aren't looking for the pitch.

Because he tends to spot it in a difficult location and break it out of the strike zone when hitters don't see it coming, Mazzaro gets great results from his curveball. Hitters have a tough time hitting when it's in the strike zone, and it breaks so late that they can't check up their swings on the occasions Mazzaro buries it out of the zone.

Ultimately, the pitch plays up because Mazzaro catches hitters off guard with it and spots it well, but the late movement and deception on the pitch also help to make it effective.

Mazzaro's curve is a perfect illustration that the scouting consensus isn't always right. Sure, it doesn't have as much movement as most curves, and if he hung the pitch, it would get crushed.

But Mazzaro doesn't use the curve as a strike-one pitch. He uses it to get strikeouts down and away, and in that role, the properties of the pitch and Mazzaro's command of it make it one of the best curves in the majors.

Next time you read that a pitcher has a "plus pitch," don't automatically assume that means that pitch will play well in the majors. Just because a pitcher has a "below-average" pitch doesn't mean it won't play in the majors. 

It's all about how the pitcher chooses to use what he has. Mazzaro chooses to throw a ton of sinkers, so even though the pitch is pretty good in itself, it turns out badly. He chooses to use the curve in a very specific, defined role it's well-suited for, so it turns out well.

How good the pitch is in itself ultimately doesn't matter as much as you'd think. What matters more is the placement of pitches and the pattern they're thrown in. That's why Jamie Moyer succeeds and Homer Bailey doesn't, and that's why Mazzaro's curve is 4.5 runs better than his fastball.


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