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You need look no further than this year's American League Championship Series to see the value of the swinging strike. Royals fans threw their arms up in the sixth inning of Game 5 after some questionable calls by Dan Iassogna, only to clinch the series two days later thanks in part to some generous calls by Jeff Nelson in the top of the ninth.
As the era of the strike out marches steadily on, the swinging strikeout rate climbs as well, increasing to a modern high of 10.7% this season. It should be no surprise that in the postseasons, when the best teams select their best arms to carry the bulk of the innings, swinging strike rates are even higher.
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So far this postseason, pitchers have racked 1.4 percentage points more swinging strikes than they did during the regular season, giving us an outside shot at seeing the greatest difference between the two seasons since 2010 (2.0%). This may be especially true given the current leaderboard, provided (along with all the data for this article) by the Savant of Spray Charts himself, Daren Willman:
Most swing & misses induced during the playoffs deGrom 58 Syndergaard 42 Arrieta 41 Estrada 40 Greinke 36 Price 34 Herrera 32 Harvey 32
— Daren Willman (@darenw) October 26, 2015
The list reads like a who's who of 2015 playoffs workhorses. The swinging strike leader deGrom has thrown the second most pitches this postseason, while Price — currently the pitch count leader — tops the list. Run through the rest of the list and Syndergaard, Arrieta, Estrada, Greinke , and Harvey are also each in the top 15 for pitches thrown. But one of these names is not like the others. One of these names just doesn't belong.
While he does have a place on the leaderboard, Kelvin Herrera is different from the rest of the group. Somehow a relief pitcher — sorry, a dedicated relief pitcher — is tied with Matt Harvey for 7th-most whiffs despite throwing 70 fewer pitches. If you consider swinging strike rate, rather than the raw statistic, Herrera is the clear leader, getting swings on 25.8% of the pitches that he's thrown this postseason.
The chart below shows swinging strike rate in both the playoffs and regular season for the Royals and Mets pitchers who have thrown at least 50 pitches this postseason. The far left-hand column shows the pitcher's rank compared to all pitchers who have eclipsed that pitch threshold these playoffs.
| Name | Total Playoff Pitches | SwStr% - Playoffs | SwStr% - Regular Season | Δ SwStr% |
|---|---|---|---|---|
| Kelvin Herrera | 124 | 25.8% | 14.5% | 11.3% |
| Danny Duffy | 54 | 24.1% | 9.5% | 14.6% |
| Noah Syndergaard | 233 | 18.0% | 13.3% | 4.7% |
| Jacob deGrom | 326 | 17.8% | 14.0% | 3.8% |
| Wade Davis | 94 | 17.0% | 12.7% | 4.4% |
| Ryan Madson | 100 | 17.0% | 14.1% | 2.9% |
| Matt Harvey | 194 | 16.5% | 12.8% | 3.7% |
| Tyler Clippard | 70 | 15.7% | 12.9% | 2.8% |
| Chris Young | 148 | 15.5% | 10.5% | 5.0% |
| Luke Hochevar | 63 | 14.3% | 11.4% | 2.9% |
| Jeurys Familia | 130 | 13.8% | 16.9% | -3.0% |
| Kris Medlen | 70 | 11.4% | 9.3% | 2.2% |
| Bartolo Colon | 81 | 11.1% | 7.0% | 4.1% |
| Yordano Ventura | 310 | 10.0% | 11.1% | -1.1% |
| Johnny Cueto | 263 | 8.4% | 10.8% | -2.5% |
| Steven Matz | 161 | 8.1% | 9.5% | -1.5% |
| Edinson Volquez | 286 | 7.3% | 10.2% | -2.9% |
So how do the rest of the Royals and Mets pitchers stack up against Herrera? Perhaps surprisingly, Danny Duffy has been used just enough to meet the threshold and trails only his flame-throwing teammate. For the Mets starters, Syndergaard has had the highest whiff rate, and 5th highest overall. Syndergaard trailed only deGrom in total swinging strikes, but also threw 103 fewer pitches.
Look through the table and you'll notice that all but five pitchers have posted higher swinging strike rates this post season than they did during the regular season. This hints at a second reason that swinging strike rates are higher in the postseason than they are the rest of the year. Not only are teams able to cull the weaker members of their rotation, putting them into the bullpen where their stuff often plays up, but the teams that are getting more swinging strikes may also continue to advance.
This World Series, the Mets and Royals pitchers aim to continue what they have done more than any other team during the playoffs: induce swinging strikes. Kelvin Herrera has led the Royals to a total of 196 this postseason. deGrom has led the Mets to 193. The Royals get their swinging strikes from the bullpen. The Mets get theirs from their rotation. These pitching staffs are completely different, yet they've ended up in the same place.
. . .
Matt Jackson is a featured writer for Beyond the Box Score and a staff writer for Royals Review. You can follow him on Twitter at @jacksontaigu.