Two Very Different Cutters

On the surface Mariano Rivera and Mark DiFelice should be two of the most similar pitchers in the game. They are both right-handed relief pitchers who throw a cutters almost exclusively, over 90% of the time. No other pitcher throws the cutter that often, and only a handful of pitchers throw any one pitch close to as often as Rivera and DiFelice throw their cutters. But there is a startling difference between the two: DiFelice has one of the largest platoon splits of any pitcher, while Rivera has a reverse platoon split. Two pitchers throwing the same type of pitch almost exclusively and they are at opposite ends of the platoon split spectrum. Obviously there must be something very different about their cutters.

The most obvious difference is velocity. Rivera throws one of the fastest cutters in the game working in the low 90s, while DiFelice one of the slowest working in the low 80s. I am not sure how velocity influences the platoon split.

The movement of the two cutters is also different.


Both cutters have positive horizontal movement (tailing away from RHBs), which is uncommon for cutters. There is some overlap, but, generally, Rivera’s cutter has more ‘rise’ and slightly more horizontal tail.

Here is a breakdown of their cutters by some different metrics against RHBs and LHBs.

| Rivera Cutter   |    RHB |    LHB |
| Run Value       | -0.018 | -0.032 |
| In Zone         |  0.513 |  0.508 |
| O-Swing Rate    |  0.360 |  0.373 |
| Whiff Rate      |  0.260 |  0.188 |
| Pop Out per BIP |  0.123 |  0.133 |
| BABIP           |  0.299 |  0.245 |

Rivera’s cutter is great against lefties and righties, and here you can see its incredible reverse platoon split (the run value is the average change in run expectancy after the pitch, so negative is good for the pitcher). Interesting the reverse split does not come from strikeout or walk rates (Rivera strikes out more RHBs and walks about the same), but from balls in play. Somehow balls in play off his cutter from lefties have a higher pop out rate and much lower BABIP than from righties.

| DiFelice Cutter |    RHB |    LHB |
| Run Value       | -0.031 |  0.015 |
| In Zone         |  0.550 |  0.550 |
| O-Swing Rate    |  0.383 |  0.330 |
| Whiff Rate      |  0.373 |  0.216 |
| Pop Out per BIP |  0.188 |  0.077 |
| BABIP           |  0.200 |  0.333 |

DiFelice’s cutter against righties is amazing: huge o-swing (percent of pitches out of the zone swung at), whiff (percent of swung at pitches that are missed) and pop-out rates. But unlike Rivera things fall apart against lefties, with each of these rates dropping dramatically.

Next I checked the location of their cutters in the strike zone versus right-handed and left-handed batters.


I think this is the key. Rivera works both edges of the strike zone against both lefties and righties. Since he can routinely place pitches on either edge his cutter can be successful against both. DiFelice, on the other hand, pounds his ‘sinking’ cutter down-and-away against righties. It seems that because of his cutter’s ‘sinking’ and tailing away movement (compared to a normal fastball) righties routinely swing at these pitches out of the zone. And even if they make contact the pitches are all down-and-away where most hitters can generate little power. Lefties, though, could generate tons of power from this down-and-in location and it looks like he cannot locate the pitch down-and-away against lefties. Instead most of his pitches to lefties are in the heart of the plate, not a good place for a low-80s cutter.

So it looks like the major difference is the ability to locate coupled with speed. Rivera can hit both edges routinely against both righties and lefties with his blazing cutter and somehow the pitch depresses lefties BABIP, which results in his reverse platoon splits. DiFelice can routinely locate the pitch down-and-away to righties, but has no place to go against lefties other than right down the middle.

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Dave Allen's other baseball work can be found at Baseball Analysts.

11 Responses to “Two Very Different Cutters”

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  1. Matt says:

    The cutter to LHB depresses BABIP because lefties are *always* getting jammed. Seldom does a lefty make good contact against the pitch. It’s not a mystery.

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  2. Tom B says:

    Pretty crazy you wrote this today, last night after the Yankee game me and my friends were delving into the majesty that is Mariano Rivera…

    This freak of nature doesn’t even HAVE “splits” at all. His career numbers are almost identical regardless of home/away, day/night, lefty/righty. The only split that he even shows separation in is save/non-save.

    In other words, I heart Mo.

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  3. Adam says:

    Come on… was anyone really aching for a comparison of Rivera and DiFelice’s cutters? Calling this post relevant to anything is a real stretch. There is such a thing as overanalysis.

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    • Garrett says:

      Really? I love this article, and I was curious as to how two pitchers with such radically different velocities can have such successful one pitch repitoires. Great work here, I think this is a cool idea for an article.

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    • Matt Harms says:

      I think is really cool, personally.

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    • Mike I says:

      There was a very interesting article here maybe a week or two ago on DiFelice’s cutter, which is starting to gain a lot of attention (namely because it’s the only pitch he throws, it’s slow, doesn’t have a ton of movement, yet DiFelice has had amazing success). So that is part of what prompted this article, I guess. I personally find both of these guys’ cutters fascinating, considering the outrageous success they’ve had with it, so naturally it seemed like a fascinating article to me. But I suppose that some people just like to bitch about free content.

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  4. Joe S says:

    The chart for Rivera against LHBs is amazing. You can see a gap between the inside and outside of the plate, that is some serious control.

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  5. nick says:

    “Somehow balls in play off his cutter from lefties have a higher pop out rate and much lower BABIP than from righties.”

    I agree, “somehow” is a weird word to use here–it seems entirely intuitive–unless “somehow” signifies the sabermeteric “all BABIP variations are random until proven otherwise”?

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    • Alireza says:

      “Somehow” isn’t really used properly, because we all know why Rivera is so effective against lefties. They have two choices with him: take a called strike or swing and get jammed. They may well make contact, but they will end up getting sawed off and/or popped up.

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