The Cutter: Magic Pitch

With the recent success of Andy Sonnanstine and John Danks throwing the cutter, I thought it would be interesting to research what effect the cutter has on a pitchers career. Everyone knows the story of Mariano Rivera learning the cutter and going on to be the most successful closer in major league history, but still relatively few pitchers throw a cutter.

So I decided I would take a look on what effect throwing the cutter has on a pitcher the first year that they use it significantly (more than 10% of the time).

For this project, I took every pitcher that threw more than 10% cutters in 2008, and look at their pitch selection data to find the exact date they started throwing their cutter (a significant amount). For example, Andy Sonnansine threw some cutters in 2007, but he started throwing a significant amount of cutters in 2008. Some pitchers were not included in this because they either started throwing their cutters in the minor leagues, or they started throwing them before baseball info solutions started counting cutters (2004).

So first I took the statistics of these pitchers the season before they started throwing cutters. Then I took the statistics for the season directly following the point where they started throwing cutters. Below:

	K/9	BB/9	K/BB	HR/9	ERA	WHIP	GB%	Value
Pre-cutter	6.79	2.97	2.28	1.24	4.49	1.35	44%	$4
Post-cutter	7.03	2.27	3.09	0.99	3.88	1.23	44%	$16

 

My first impression was absolute shock. I was expecting there to be a positive impact, but massive across the board improvement like this is amazing. The pitchers without a cutter would have an ERA+ around 95, 5% worse than the league average pitcher. After learning the cutter? 111, 11% better than the league average.

Let’s look at where our pitchers improved.

K rate: This is where I thought we would see the most significant spike, and we did see a drastic increase. 6.79 to 7.03 is a big difference.

BB rate: This was extremely surprising. When you think of the cutter, you think of guys like Mariano Rivera racking up the strikeouts. Evidently, it is a very easy pitch to control.

GB%: Now here is something else that surprised me. I thought GB% would increase with the cutter, but in fact it stayed the same (actually decreasing by a couple tenths of a percent). However, pitchers HR rates plummeted. This was not due to a drop in FB% or a spike in LD%, as both rates remained constant. Pitchers HR/FB rates just dropped significantly when throwing the cutter. While stats like hit rate and hr/fb rate are usually not significantly effected by the pitcher, pitchers that throw a cutter demonstrate a much lower HR/FB rate.

Also interesting is that almost every pitcher improved in a very similar manner. There was one notable exception; not all pitchers saw an increase in K rate, however most pitchers did. Take a look:

	K rate	BB rate	K/BB rate	HR Rate
Improved	60%	93%	80%	80%

 

Most pitchers, but certainly not all of them, improved their K rate. All but 1 pitcher improved their control, and all but 3 pitchers improved their K/BB rate and HR rate. All in all massive across the board improvements.

Probably the most amazing thing about this is that less than 17% of starting pitchers in major league baseball threw more than 10% cutters last season. The cutter seems to be a free pass to becoming a massively better pitcher in every single aspect of pitching, yet most pitchers do not throw it.

This information also has massive predictive value. If you here that a starting pitcher is working on a cutter, it is a safe bet to expect improvement across the board. Just as an example, take a look at what the cutter did for Jamie Moyer.

2004: 44 HR, 5.24 ERA
2005: 23 HR, 4.28 ERA

So even a 40+ year old pitcher can learn a cutter, and instantly improve drastically in at least one aspect of the game, making them a significantly better pitcher. Moyer didn’t even throw that many more GBs, he just learned a pitch that seems to be magic for MLB pitchers. And young pitchers can be helped by this too. Take a look at John Danks from last season:

2007: 7.06 K rate, 3.5 BB rate, 1.81 HR rate, 5.50 ERA.
2008: 7.34 K rate, 2.6 BB rate, 0.69 HR rate, 3.23 ERA.

As for the fantasy value of this information, there is one pitcher that will be throwing a significant number of cutters this season that did not in previous seasons. That pitcher is Kyle Davies. Davies, a former top prospect, has struggled the last few seasons but there was some reason to hope coming into 2009. And so far, he has delivered (although in a small sample size). In one start he went 7 innings, struck out 8, walked 2, and didn’t allow a home run. This is most likely a sign of things to come.