Searching for a Comp for the Ultimate Signature Pitch

Apparently this is the week where I do whatever anyone says. Yesterday I identified some comps for various signature pitches around the league. In the subsequent comments, a request:

Well-Beered Englishman says:
As long as we’re making requests, I say hop in the time machine and compare somebody to Mariano.

So it shall be. Let’s see if we can find a decent comparison for Mariano Rivera’s cutter, which has been the most signature of signature pitches. There’s been no greater example of hitters being unable to do much despite knowing exactly what’s coming. With Rivera, there wasn’t a lot of mystery. Just precise, pinpoint location, in areas that ensured his success.

In terms of style, the best comparison for Rivera is probably Kenley Jansen. Jansen dominates with a cutter and little else, and if that sounds familiar, it’s because that was Rivera’s whole game. But this investigation is a little different: this is looking for cutters most like Rivera’s cutter. Research was performed using the Baseball Prospectus PITCHf/x leaderboards and Brooks Baseball player pages.

The first step was getting Rivera’s information. I decided to use his data from 2011, because that fell within the PITCHf/x era, and it was a typical dominant Rivera year. For those of you who haven’t followed the process, I’m looking at just velocity, horizontal movement, and vertical movement, for pitchers of the same handedness. After plugging in Rivera’s numbers, I assembled numbers for all righties who threw at least 50 cutters in 2014. Then I added in sliders, because sliders and cutters are thrown similarly and they can be hard to tell apart.

For each of the three categories, I calculated the z-score separation between Rivera and the given pitcher. I took the absolute value of each, then I just added them together to get a comparison rating. The closer the number is to 0, the better the comparison it is. Here now: the top five best comps, based on the above method.

Pitcher	Pitch	Velocity	Horizontal	Vertical	Comp Rating
Mariano Rivera	CT	92.3	2.2	7.1	–
Logan Ondrusek	CT	91.7	1.7	7.8	0.7
David Robertson	CT	92.6	2.4	9.1	0.9
A.J. Ramos	CT	91.5	1.2	6.5	1.0
Danny Farquhar	CT	90.2	1.5	7.2	1.1
Wade Davis	CT	92.6	2.5	4.8	1.1

Just like everyone suspected: it’s Logan Ondrusek! The most comparable cutter to Mariano Rivera’s signature cutter is apparently thrown by Logan Ondrusek. Now that actually is interesting, and I could stop here if I wanted, but let’s take this a little further. I want to note that I’m not convinced A.J. Ramos’ cutter is a different pitch from his fastball. Whatever the case, in 2011, Rivera threw his cutter about 88% of the time. According to Brooks Baseball, here are the five cutter frequencies:

Robertson: 62%
Farquhar: 56%
Davis: 20%
Ondrusek: 15%
Ramos: 7%

Those are some mighty big spreads, and some mighty big differences. For a couple guys, the cutter is a primary pitch, as it was with Rivera. But for the other three, the cutter looks like a secondary weapon. And I don’t think those would make for fair comps if we’re talking about maybe the greatest pitch of all time. I want to hold this method to a higher standard. It seems like the best candidate here would be Robertson or Farquhar.

Keep going. Let’s look at some measures of consistency. For each pitcher, one standard deviation of cutter velocity:

Rivera: +/- 1.06 mph
Robertson: +/- 1.17
Farquhar: +/- 1.23

Not bad — Rivera shows up as the most consistent, and then Robertson ranks a little ahead of Farquhar. Horizontal release point, throwing to righties:

Rivera: +/- 0.18 inches
Robertson: +/- 0.14
Farquhar: +/- 0.21

The same, throwing to lefties:

Rivera: +/- 0.16 inches
Robertson: +/- 0.15
Farquhar: +/- 0.18

And now vertical release point:

Rivera: +/- 0.14 inches
Robertson: +/- 0.10
Farquhar: +/- 0.14

Wouldn’t you know it, but in some ways, Robertson was a little more consistent than Rivera. At least, in Robertson’s 2014, relative to Rivera’s 2011. And I think Robertson gets an edge over Farquhar. His cutter is a slightly better match, he throws it slightly more often, and he throws it with slightly more consistency. I came into this looking for the best comp for Mariano Rivera’s cutter. The method led me straight to the guy who replaced him.

Rivera:

Robertson:

There are differences, of course. Rivera was trying to throw cutters. With Robertson, it seems a lot of the cutting movement has just come naturally. Rivera wasn’t able to teach his cutter to Robertson; Robertson, also, is appropriately humble.

Of all the Yankees who’ve studied the great cutter, David Robertson has come closest to copying it. He says, “On a good day, every once in a while, I’ll throw one like Mariano’s.”

And don’t forget that Rivera would sometimes throw nine cutters out of ten pitches. For every three Robertson pitches, he’ll mix in a curve. But it is clear that Robertson’s cutter has been in development — it hasn’t always been like this. It’s become more like Rivera’s cutter over time. A table of average movements:

Season	Horizontal	Vertical
2008	-0.4	11.0
2009	0.6	10.9
2010	0.3	10.7
2011	0.4	10.1
2012	1.4	9.3
2013	1.2	9.0
2014	2.4	9.1

Something seemed to click between 2011 and 2012. Robertson tweaked his cutter, and he simultaneously managed to trim his walk rate. This past year, he added even more cut than he already had. While Robertson has always been successful, he appears to still be learning, and there are worse things than gradually becoming more and more similar to the greatest relief pitcher in the history of the sport.

Still, Robertson’s cutter isn’t Rivera’s cutter. Just because it’s the closest comp doesn’t mean it’s identically good, and Robertson can’t match Rivera’s location. Nobody can. Consider these heat maps, showing cutters from Rivera’s 2011 and Robertson’s 2014. Facing right-handed hitters:

Facing left-handed hitters:

Rivera lived in the same two places. He was famous for it. Robertson’s patterns are more scattered, and as a result, Rivera threw 17% of his cutters in what I’d loosely define as the heart of the strike zone. Robertson last year came in at 22%. Over the whole PITCHf/x era, Robertson is at 22%; Rivera comes in barely above 15%. With his cutter, Rivera seldom made mistakes. With his cutter, Robertson also seldom makes mistakes, but he does make more of them, maybe once or twice per 20 pitches, and that’s meaningful given the volume of pitches thrown in a season. No one could locate like Rivera. It’s unfair to even try to hold Robertson to the same standard.

And he should be pleased for coming this close. The most dominant cutter in the game today belongs to Kenley Jansen. Yet the cutter that most resembles Mariano Rivera’s cutter belongs to David Robertson. It’s not exactly the same pitch. It’s not exactly as effective. Just, consider who we’re comparing to. Almost doesn’t only count in horseshoes and hand grenades. It also counts in comparisons to Mariano Rivera. At the end of the day, you have to be reasonable.