Archive for starting pitcher

Two weeks ago, I wrote about the importance of evaluating expected strikeout rate (xK%) in the context of each pitcher’s respective histories. In other words, xK% on its own can only tell you so much about a pitcher’s chance and magnitude of regression toward the mean.

And last week, I refined the expected walk rate (xBB%) metric for pitchers by adding a proxy for pitch sequencing in the form of percentage of counts that reach 3-0 (“3-0%”). This helped better explain the model’s fit with respect to the data, as pitchers who worked into more 3-0 counts tended to walk more batters. (Who knew?)

The logical next step is to combine the two aforementioned analyses: 1) comparing xBB% to BB% 2) for each pitcher over time. I’ll reiterate a couple of key points. Calculating a pitcher’s xBB% can give us a decent idea of how lucky or unlucky he may have been during a given season. Calculating his xBB% and comparing it to his actual BB% on an annual basis can give us a better idea of truly how he typically performs against his xBB% — that is, if he consistently outperforms his xBB%, perhaps the difference between his xBB% and BB% is not a matter of luck at all but a skill or characteristic not captured by the variables specified in the xBB% equation.
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I’d like to talk to you about Dellin Betances.

Wait! Wait. No. No, I wouldn’t. I’d like to talk about Mike Podhorzer first. Mike has published a lot of great work covering the fundamentals of the xK% (and xBB%) metric for pitchers (and hitters), so if you are unfamiliar with or falling behind on his work, I recommend you first click here, here or here. But if you’re lazy, the short of it is: xK%, or expected strikeout rate, is an equation birthed from a linear regression that measures how a pitcher’s looking, swinging and foul-ball strike rates as well as overall strike percentage correlates with his strikeout rate. It doesn’t predict future strikeout rates as much as it retrospectively adjusts past strikeout rates; thus, it is a good tool for identifying pitchers who potentially benefited (or suffered) from good (bad) luck in a previous season – say, 2014.

Like many other metrics completely unrelated to xK%, however, there is evidence that certain players consistently out-perform (or under-perform) what their xK% rates predict their actual K% rates should be. (Mike alludes to this trend in his quip about Jeremy Hellickson, a xK% underachiever, in one of the articles linked above.) Similarly to how a power hitter will post consistently higher ratios of home runs to fly balls (HR/FB) than a non-power hitter, or how Mike Trout will probably post some of the highest batting averages on balls in play (babip) in the league for years to come, it appears there is some skill, or perhaps a particular characteristic, inherent to pitchers who consistently best, or fall short of, their xK% rates.

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Last week, I talked about the youngest regular position player in the Appalachian League: Mets shortstop Amed Rosario, who was named the circuit’s top prospect by Baseball America after the season. Sticking with the youth theme in the Appy, this week I’m going to focus on the league’s youngest regular starting pitcher, 18-year-old Rays righthander German Marquez. Marquez did not appear on BA’s top 20 postseason Appy prospects, but with solid performance (3.50 FIP), a nice arsenal, and plenty of time and room to develop further, I’d argue he deserves to be placed squarely among the circuit’s most intriguing players, and is definitely a player to watch.

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Every year, there are always several prospects who emerge from obscurity to post majestic statlines in the lower levels of the minor leagues. As such a player strings together an extended period of statistical superiority, questions of his legitimacy as a potential impact player arise–do the numbers merely reflect hollow dominance of fatally flawed, cupcake opponents, or are they a sign of a player emerging as a prospect to watch?

In the immediate aftermath of such a statistical rise, there is always a need for firsthand observation of the player to contextualize both his present excellence and future potential. One player very much in this mold is White Sox pitching prospect Adam Lopez.

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OK, so the language in the title might be a bit inflammatory.  I can’t, with 100% certainty, say that I absolutely, positively won’t draft these guys, but based on the current chatter and their ADP rankings, they will not be targets for me.  Now, if they somehow slipped a few rounds and it looks like they could, potentially, be a bargain, then I might think otherwise, but that’s a pretty big “if” for me right now.  Here’s who I’m avoiding… Read the rest of this entry »