From the Catcher’s POV

As both Dave Cameron and Mike Petriello have noted earlier today in different ways, the Royals bullpen has contributed substantially to the club’s successful — and largely unimpeded — run through the 2014 postseason. In their victory over Baltimore on Wednesday, for example, the triumvirate of Wade Davis, Kelvin Herrera, and Greg Holland combined for 3.2 scoreless innings. As noted by Cameron, that same threesome accounted for over 40% of the innings thrown by Royals pitchers during the Championship Series.

Herrera accounted for 1.2 of those innings on Wednesday, and he finished his outing in a notable way, first by means of this 1-1 pitch to Caleb Joseph:

And then by way of a nearly identical pitch right after that, for the strikeout:

Despite the velocity readings — in fact, PITCHf/x classifies them as fastballs — those are both examples of Herrera’s changeup. As illustrated in the second of GIFs above, the strikeout produced some emotions inside of Kelvin Herrera. Another person inside of whom the latter changeup appeared to produce emotions was Ron Shah, who writes about prospects for FanGraphs.

To wit:

A righty on righty down and in changeup may be my favorite pitch.

— Ron Shah (@Rontrarian) October 16, 2014

I can’t speak to why precisely Shah likes the pitch. What I can say about the low-and-in changeup, however — from right to righty — is that it’s not a particularly common one.

As the graph below indicates, both of Kelvin Herrera’s changeups to Caleb Joseph crossed the plate in what’s known as Zone 13 in the parlance of PITCHf/x. It’s the area both down and in to a right-handed batter (or outside and down to a lefty).

See here:

Over the course of the 2014 season, right-handed pitchers threw a Zone 13 changeup to left-handed batters about 12,500 times; to right-handers, however, just slightly less than 3,400 times — this, despite facing more right- than left-handed batters collectively over the season. Generally speaking, the changeup is a pitch employed to neutralize a hitter’s platoon advantage. Pitchers who lack one (i.e. who lack a changeup) are generally regarded as candidates for the bullpen only, where their exposure to opposite-handed batters can be more carefully controlled. (There are exceptions to this, but the general idea holds.)

Herrera appears to have had some success with the Zone 13 changeup to right-handed batters this year. According to Baseball Savant — from which site, I should note, most of this data is stolen — Herrera has thrown 1257 total pitches in 2014, accounting for the regular season and playoffs. Of those pitches, 66 have been changeups to right-handers and 24 of those have been Zone 13 changeups to right-handed batters.

Here are the results:

The relationship between swinging strikes and strikeout rate is very high, producing an r-squared of 0.69, for example, in one study by Bradley Woodrum. Herrera’s low-and-in changeup to right-handed batters has produced a 50% swinging-strike rate in 2014. Consider, by way of comparison, that Aroldis Chapman, who stuck out over half the batters he faced this season, produced a swinging-strike rate of just 20.0% in 2014. Indeed, using the algorithm from Woodrum’s post, a swinging-strike rate of 50% should theoretically produce a 98% strikeout rate. There are obviously a lot of reasons why Kelvin Herrera won’t strike out 98% of the batters he faces. What his success tells us, however, is that the pitch itself is a quality one and that he’s used it well.