Command PostMay 25, 2007
Dangerous Curves
By Joe P. Sheehan

Watching Rich Hill pitch reminds me of watching Barry Zito and I'm sure I'm not the only one who sees the similarities. Both are tall left handers with big, looping curveballs, but they have more in common than their physical appearances. Both pitchers are extreme fly ball pitchers, with 61% of balls in play against Zito in 2007 being fly balls and 65% for Hill. Despite the platoon disadvantage, left handed hitters have actually posted better offensive numbers against Zito and Hill than right handed hitters have. Their careers haven't followed similar trajectories, Zito made his major league debut at age 22 and had a Cy Young by 24, while Hill pitched in the minors until he was 25, hampered by injuries, but both lefties have a similar repertoire of pitches and appear to pitch in a similar fashion. Furthermore, the curveballs thrown by the two are practically begging to be analyzed via Enhanced Gameday. I've wanted to look closer at Zito since I had noticed his unique release point during the 2006 playoffs (more on that in several paragraphs) and comparing his curveball to Hill's was high on my to-do list for Gameday projects, so I figured I'd knock off both things in this article.

First off, here's a chart showing Barry Zito's start on May 15th in his return to Oakland. Zito struggled in this start, going four innings, while allowing seven runs on seven walks and six hits. From this chart you can see a couple of basic features of Zito's pitches. His fastball is pretty straight, although it does have some movement in on left handed hitters, the normal direction for a left handed pitcher's fastball to move. I'm not very confident in my identification of his slider and changeup, but based on what I have, the slider moves in on lefties, while his changeup moves slightly away. Zito's curve is the pitch I really want to look at in this article, so it was rather disappointing to see that Zito only threw 11 in the game. The curve ends up slightly more than 10 inches lower than a non-spinning pitch would, evidence of the tremendous topspin Zito imparts on his curve. Is a 10 inch "drop" an impressive number? The only way to check that is to examine other curveballs.


Before I move onto Rich Hill's curve though, I wanted to look at Zito's release point. During the 2006 playoffs, I noticed that Zito's release point was much closer to the center of the pitching rubber than I would have thought a left hander would be. His release point was very close to that of a right handed pitcher, and I speculated that it could be the reason left handed hitters had success against him. Here's a chart comparing his 2007 release point to his 2006 playoff release point, as well as the release point of Dan Haren and Joe Kennedy for perspective. All four release points were captured in Oakland, with the 2007 ones from consecutive days in an effort to control for park changes.


Even after accounting for the different versions of technology used, in 2007 Zito still releases the ball close to the middle of the rubber, but he's not as extreme as he was in the playoffs and other pitchers actually have similar release points.

Getting back to Hill, here's a chart showing his pitches from his start on May 22nd in San Diego. Despite striking out eight batters, Hill allowed five runs in six innings and took the loss in this particular start. Hill throws three or four pitches, clearly a fastball and curveball, as well as possibly a changeup and slider. I have the same uncertainty with classifying Hill's changeup and slider as I did with Zito and in the end I called one of the groups his changeup, while calling the other unknown. Looking at Hill's fastball, it has similar horizontal movement in toward left handed batters as Zito's had, although Hill's had a wider range of breaks. Even though Hill's fastball was faster, Zito's fell less vertically, possibly indicating greater backspin on the ball for Zito.


Hill's curveball is tremendous. The biggest difference between his curveball and Zito's is that his has more horizontal movement. In addition to breaking 12 inches down, Hill's curve moves roughly seven inches away from left handed hitters. Zito has the same drop on his pitch, but only gets three inches of movement away from left handed hitters. With everything else (pitch speed, release point, and vertical break) being just about equal, a curve that breaks laterally as well as vertically is harder to hit than a curve just moving vertically. The horizontal break also helps classify the curveballs from the hitter's point of view, with Zito's being 12-to-6, while Hill's is more of a 12-to-7 or 8.

Name         Pfx_x      Pfx_z      Speed
Zito        -3.0"      -11.3       72 MPH
Hill        -7.1"      -12.3       74 MPH

The chart above shows the median values for several variables that describe Zito and Hill's curveballs. Do other pitchers throw similar types of curveballs? After looking at some pitchers who throw curveballs (and doing a little fishing in my database) I found several pitchers that threw comparable curves, but Zito and Hill were still unique. The chart below shows the median values for the pitchers I looked at.

Name Pfx_x Pfx_z Speed Hand Number of Curves
Wolf -5.8" -6.5" 67 MPH L 116
Blanton 5.1" -8.6" 74 MPH R 108
Arroyo 9.8" 2.5" 76 MPH R 36
Sheets 2.9" -4.8" 80 MPH R 29
Meche 2.0" -12.6" 79 MPH R 13

Gil Meche had a very similar curveball to Zito and Hill, although he didn't have as much horizontal movement and threw only 13 of them in the start I examined. In this chart, negative pfx_x values indicate movement in to right handed hitters. Bronson Arroyo had the most horizontal movement of any curveball, but interestingly, actually had his curve end up higher than a non-spinning pitch would have. Either he was hanging his curve on May 16th, or there was something wrong with the tracking system in San Diego on that day.

Obviously Hill and Zito have very unique curveballs. Even after looking for pitchers with the greatest vertical drops, I couldn't find other pitchers with similar curveballs. One thing I would like to look closer at is which pitches Zito and Hill actually get their fly balls on. Are the fly balls a direct result of curveballs or are they the result of a general pitching pattern? I don't have enough curveballs in my database from Zito and Hill to really get a good read on it yet, but I would guess the fly balls are more a result of a pitching pattern than actual pitches.

I had a couple of things I wanted to mention before I finished. I have more data for sinker ballers now, with Webb having a couple of starts and Wang making his debut in an Enhanced stadium. I'm going to look at sinkers again in the future, and hopefully should have something new to say. I also noticed that Wakefield had several starts in Toronto, also an Enhanced stadium, and looking at his pitch charts, its not surprising that nobody can hit him when his knuckleball is working as the break values on his knuckleball look virtually random. Certain hitters also finally have enough enhanced pitches that I can look at batting average on balls in play from the hitter's perspective and have it mean something.


Excellent article once again Joe. One of the things I noticed is that Phil Hughes in his May 1st start ( had an average vertical drop (pfx_z) of -9.75 (on downward breaking pitches), good for fouth in my database behind Hill at -12.4, Zito at -11.9 and Meche at -10.0 with Brandon McCarthy, Joe Blanton, Justin Duchscherer, Justin Germano, and Felix Hernandez coming in behind.

Also, taking a quick look I found the following outcomes on all pitches with a vertical break of 6 or more inches (for the most part curveballs).

Outcomes Pitches pfx_z Pct
Ball 567 -8.23 38%
Called Strike 275 -8.14 18%
Foul 207 -8.28 14%
In play, no out 55 -8.48 4%
In play, out(s) 180 -8.00 12%
In play, run(s) 27 -8.45 2%
Swinging Strike 181 -7.99 12%

Looking at the balls put into play 50% were ground outs, 16% were fly outs, 21% were singles (can't tell of what type), 8% were extra base hits, and 5% were line outs. It would seem that a healthy percentage of curveballs turn into groundballs.

Wow. I literally had no idea that this sort of data existed.

Can someone chime in and explain the nature of the technology that captures this information?

That is good analysis. I can't add much to it, other than to say I am looking forward to seeing the same for sinkerball pitchers.

(Also, how is the enhanced gameday pitch data downloaded?)

What type of FB do Zito and Hill throw--2 or 4 seamer? Maybe the flyball tendency is coming from the fastball location rather than the curveball. Not all pitchers who feature a big curve are flyball pitchers.

Gibson Rules,

take a look at my column on BP from a couple weeks ago for some background information.


I more or less took guys I knew threw curves and added Meche and Wolf after some digging...I'm wasn't set up to find the average break like you did. The chart was pretty cool...I think that maybe one reason for the high percentage of breaking balls being called balls is that they were waste pitches throw to try to induce a swing.


Here's a link to where I download the data.

I dont know what type of fastballs Zito and Hill throw. I dont think that theres one particular reason for the flyballs, but more the general pitching pattern. I don't think there is a "reverse sinker" that can produce fly outs in high rates. When I have more than 11 curves for Zito, I'll look at him again and see what pitches he gets his fly outs on.

Don't know if this will help your analysis, but from what I remember, the A's loaded their lineup with lefty hitters against Zito in the start that was analyzed above. Perhaps that had an effect on his use of his curve?