Archive for whiff rate

Shortly after the onset of last season, I dug into pitch-level statistics to see how much swinging strike rate (SwStr%), ground ball rate (GB%), and isolated power (ISO) varied by pitch type. I felt inspired after analyzing Madison Bumgarner before the 2018 season and noticed his fastball, once elite, was utterly broken after his dirt bike accident. (See his 2018 player caption and this July post in which I followed up MadBum’s lack of progress.) I felt encouraged by the praise the post received from readers and fellow analysts alike for the clarity it provided. I’d like to think it helped move the needle, even if only slightly, in terms of how we evaluate pitchers.

I wanted to refresh the guts of that post for the 2018 season with additional metrics. There’s not much else to discuss; this’ll be short and sweet. (I’ll toss in some gratuitous high-level analysis following these tables.)

Notes:

• All data is courtesy of PITCHf/x via Baseball Prospectus
• All tables present average rates for starting pitchers only
• Due to pitch tracking/stringing not being perfectly precise, the numbers below are highly accurate but not completely so and may not align exactly with FanGraphs’ batted ball data (for example, Baseball Info Solution strings far fewer line drives than does PITCHf/x)
• Click headers to sort!

Batted ball outcomes by pitch:

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Rob Silver, the 2016 National Fantasy Baseball Championship (NFBC) Main Event winner and high-stakes fantasy baseball extraordinaire, messaged me on Twitter a few days ago to ask a question: Which source of pitching statistics are most accurate? I’m paraphrasing. Also, I could paraphrase the question any number of ways: Which source should we be using? Which most reliably correlates with pitcher performance?

It was a question for which I had no answer. Admittedly, I use a variety of sources, none of which align with one another — something I have noticed before but about which I can do nothing but shrug and accept it as a quirk of being a sabermetrician who bears the struggle of dealing with publicly available data.

The sources cryptically mentioned above include the following:

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Normally I don’t write about bad players. It’s more of a truism than anything: writers like to analyze the breakout or peak-performance potential of top prospects or, alternatively, red flags associated with the game’s premier talents. Rarely do we write about objectively bad players.

Through 120 Major League innings (and change), Robert Stephenson has been an objectively bad starting pitcher, having compiled a 5.10 ERA, an anemic 1.63 strikeout-to-walk ratio (K/BB), and 0.1 WAR. A former 1st-round pick and a consensus top-100 prospect for four consecutive years, Stephenson quickly fell from grace after a catastrophic small-sample debut in 2016. Entering his age-25 season, though, he still has plenty of time to turn things around.

That’s the beauty of baseball: an objectively bad player can become an objectively good one, sometimes overnight. 2017 was a banner year for post-hype prospects, all of whom seemed, at one point or another, destined for eternal mediocrity and former-prospect bustitude. I think Stephenson can become an objectively good pitcher, but it’ll take work.

Here’s a top-10 list, presented ordinally and without the statistic by which I’ve ordered it, of pitchers who accomplished something in 2017, from a list of hundreds of other data points:

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A few weeks ago, I took a deep dive on Luke Weaver, budding Cardinals No. 2 and Adam Wainwright torch-taker. I came out of it reluctant to invest in him at his hefty asking price: per National Fantasy Baseball Championship (NFBC) average draft position (ADP) data, 27th among starting pitchers and 105th overall. His lackluster swinging strike rate (SwStr%) indicated to me he could not sustain his lofty 28% strikeout rate (K%) when pitchers of similar SwStr% caliber had strikeout rates ranging from 18% at worst to 25% at best. The best, in that instance, was Aaron Nola. I doubted Weaver could compare so favorably, primarily because Nola steals strikes in a way few others can.

What I failed to do — what I should’ve done — is check. Duh! I should’ve checked how often Weaver earns called strikes. So I did, and I came away feeling even more scared than before. Turns out, I’m an idiot who botched some simple arithmetic: Weaver falls just outside the top quartile of pitchers in stealing strikes, as opposed to literally 3rd-worst like I claimed in the previously linked Tweet. That would’ve been really bad. Still, this miscalculation and subsequent mischaracterization of Weaver’s ability sent me on a quest of ultimately marginal value.

The more I looked at Weaver’s plate discipline peripherals, the more I realized Weaver doesn’t coerce many swings-and-misses out of the zone. He’s actually pretty bad at it. That means he generates most of his success in the zone, which, to me, seemed unusual. I was nervous that thriving by threading the needle — i.e., pounding the zone (assuming some semblance of command) and hoping for whiffs — might be a dangerous way to live, or that, at the very least, a young pitcher for whom the proverbial book on him isn’t out yet might be subject to regression in this particular area. The freshly FanGraphs-retired Eno Sarris thought thriving in the zone is better than thriving outside the zone:

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More often than not, I write to hype a player who has wowed me in one way or another. Sometimes, I have to put a damper on things. Through 20 National Fantasy Baseball Championship (NFBC) drafts, Luke Weaver’s average draft position (ADP) stands at a pearly 111th overall and 28th among starting pitchers.

Weaver’s 36-inning debut freaked me out a bit. It was evident he could capably prevent baserunners, or, through 20% of a season, he could at least fake it. His 3.34 xFIP suggested as much, even in spite of his abhorrent 31% ground ball rate (GB%). Everything else stunk — all the luck metrics broke the wrong way in a small sample — but it was enough to suggest a bright future for the former 1st-rounder was imminent.

I planned to avoid Weaver at all costs in 2017 because of his fly ball tendencies exclusively; I simply did not want to suffer the wrath of a juiced ball because some small-sample strikeout-to-walk ratio (K/BB) goodness seduced me. Turns out, batted ball metrics can also feel the wrath of randomness in small samples, as his ground ball rate spiked to an above-average 50%. Some of the luck metrics tempered a bit, and the result was a 29% strikeout rate (K%) and defense-independent metrics that suggested he should nearly have a flat 3.00 ERA. It’s almost like there’s a reason why this 24-year-old kid was drafted in the 1st round or something.

I’m here to pump the brakes. I’m not sold on Weaver’s peripherals. I’m willing to let you convince me otherwise, but allow me to explain.

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