Since 2013, I have polled you dashingly attractive readers on which group of pitchers you think will post the better aggregate ERA post all-star break. The two groups were determined based on ERA-SIERA disparity, pitting the overperformers versus the underperformers during the pre-all-star break period.
In 2018, and again earlier this year, I reviewed how different pitch types perform by various measures including swinging strike rate (SwStr%), ground ball rate (GB%), and isolated power (ISO). In the last couple of years I have tried to emphasize heavily the importance of evaluating a pitcher on his component parts — namely, each of his unique pitches, all of which behave differently and can bring resolution to some of pitching’s more enigmatic questions and issues.
If you clicked through those links in the first sentence, you saw how breaking balls and offspeed pitches outperform fastballs by virtually every metric. With the advent of Statcast, we can not only validate my prior work, which relied on PITCHf/x data, but also dig more deeply into how each pitch type behaves according to newfangled Statcast data — namely, how each pitch performs exclusively on balls in play.
This is something I pursued preliminarily using the PITCHf/x data, by measure of ISO, but it doesn’t fully capture total production or damage allowed. Having written about Zack Wheeler the other day and in discussing how the performance of his pitches have ebbed and flowed from 2018 to 2019, I was curious to dig into pitch-specific expected weighted on-base average (xwOBA) on contact (xwOBAcon).
Here’s how every pitch type compares by xwOBA allowed. Keep in mind, xwOBA captures “deserved” total value through not only balls in play but also strikeouts and walks. Year in and year out, fastballs fare worse than the league average, whereas breaking balls and offspeed pitches perform better than average, all to varying degrees.
Zack Wheeler, prior to about two weeks ago, was an enigmatic starting pitcher on whom many fantasy owners had started to lose faith. (Such faith might again be lost after Sunday’s start, which is another issue all together.) After missing two seasons recovering from Tommy John surgery and related setbacks, Wheeler returned to the mound in 2017 only to be sidelined once more and miss almost the entire second half of that season. The prospects of him succeeding in 2018 were, frankly, not great.
Wheeler, however, came out firing, his four-seamer and two-seamer averaging 95.9 and 96.1 mph, respectively, up from 94.8 and 94.3 mph — a moral victory in its own right. The added velocity helped both pitches play up in way completely unseen the year prior, as measured by expected weighted on-base average (xwOBA) allowed:
| Pitch Type | 2017 | 2018 |
|---|---|---|
| Four-Seamer | .345 | .307 |
| Two-Seamer | .389 | .232 |
Pitchers who are adept at getting swinging strikes but not strikeouts are one of fantasy baseball’s mild annoyances. Many of us have used SwStr% as a shorthand for strikeout potential, but a few pitchers with high whiff rates fail to meet our expectations, usually because they get called strikes at a low rate. Prior to this season, Jake Odorizzi was one of those pitchers. Joe Musgrove (11.3 percent SwStr%, 19.3 percent K% in 2019) still is.
Eduardo Rodriguez does not fit this category exactly, but in the context of his past performances, he seems to be a strikeout underachiever this year. The Red Sox’s lefty entered this season with back-to-years of a SwStr% above 11 percent, outpacing the major league average for starters by more than a percentage point in both campaigns. His strikeout rates were far above average: 25.8 percent in 2017 and 26.4 percent in 2018. Yet Rodriguez achieved these rates with below-average called strike rates, with a 16.7 percent mark in 2017 and a 15.3 percent rate last season.
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7/2/19
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Paul meanders aimlessly discussing the painfully thin pool of pitching.
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I hate pitching.
OK, that’s not true, but it gets so thin so fast. I have Kyle Gibson in the top 50 for cryin’ out loud. I’m sure we’ve got a lot to talk about given that it opens up entirely after like, pitcher 25, so hit me up in the comments!
(Now with more Clev Dog!)
While we typically shout “SMALL SAMPLE SIZE” when attempting to evaluate players without buckets full of data, pitchers do offer us a wonderful number that stabilizes super quickly — velocity. Big changes here could result in a significant change in skill, ultimately affecting ERA. So let’s compare velocity over the last 14 days, which would typically include two to three starts, to velocity averaged prior. I’ll highlight the biggest gainers and losers.
Last Thursday, I identified and discussed nine starting pitchers that had improved their SIERA marks the most over the last 30 days. Today, let’s check in on the starter who have seen their SIERA marks spike over the last 30 days. Sell while you can or hold on for the return to early season form?
Yo! It’s been a hot minute (read: a month) since Brad or I published a Peripheral Prospects piece. Sometimes, life gets in the way. Such distinct absences aren’t so bad, after all — it allowed us a little more time for some of the season’s early conquests to flesh out in larger samples.
Around this time last year, I became enamored with a hitter about whom no one knew hardly anything at the time but of whom everyone has heard now: Jeff McNeil.
alonso @ AA: .315/.442/.574, 18.2% K, 16.0% BB
mcneil @ AA: .329/.405/.633, 9.7% K, 9.3% BBI DON'T CARE IF HE'S 26, GREAT HITTERS HAVE BROKEN OUT AT 27 BEFORE
— Alex "Oxlade" Chamberlain (@DolphHauldhagen) June 14, 2018
At the time, Pete Alonso was slaughtering Double-A pitching. But so, too, was McNeil, with a strikeout rate (K%) below 10% — and a higher isolated power (ISO) than that of Alonso, the Mets’ premier power-oriented prospect. Between Double-A and Triple-A, Alonso finished with the higher ISO (.295 to .274), but McNeil, thanks to superior contact skills and (non-homer) batted ball efficacy, produced a wRC+ almost 20 points higher.
6/28/19
The latest episode of “The Sleeper and the Bust” is live. Support the show by subscribing to Fangraphs! With a standard $20 membership, you help maintain and improve our database of stats and graphs as well as our staff of 8 full-time employees and over 50 contributors. The premium ad-free membership at $50 year supports site growth and also includes faster load speeds and better site performance. You can also support monthly for just $3.
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