Pitchers with Divergent Strikeout Rates (Part 1)

by
October 20, 2017

The season seems to never end for fantasy baseball writers. Once the regular season is over, it’s time to begin writing player previews for the next season. Pitchers who’ve had their strikeout (K% and K/9) and walk rates change in different directions spin me for a loop. Now, I query these schizophrenic pitchers to start the preseason previews. I’ll give a quick look at some of these pitchers. I’ll start with those pitchers who’ve seen their K% (strikeout per batter faced) drop while K/9 (strikeouts per nine innings) increase.

Two reasons exist for why the rates diverge. The key for both is increasing the number of plate appearances per innings. More plate appearances lead to their K% dropping if the strikeouts remain constant per inning. The other factor is how many hits a pitcher allows (basically BABIP). If a pitcher had good luck on balls in play and recorded more outs, they could quickly get through an inning and thereby raise their K%. Once the BABIP normalizes, the K% will drop.

While these diverging events aren’t common, they help to explain pitchers sending out mixed signals. Here are the pitchers who had diverging K% and K/9 from 2016 to 2017 and my thoughts on some.

Pitchers With Divergent Strikeout Rates
2016 2017 2016 2017 2016 2017 2016 2017
Name K% K% Diff K/9 K/9 Diff BABIP BABIP Diff BB% BB% Diff
Rick Porcello 21.2% 20.5% -0.8% 7.6 8.0 0.4 0.269 0.324 0.055 3.6% 5.4% 1.8%
Johnny Cueto 22.5% 21.0% -1.5% 8.1 8.3 0.2 0.293 0.322 0.029 5.1% 8.2% 3.1%
Jon Lester 24.8% 23.6% -1.2% 8.7 9.0 0.2 0.256 0.310 0.055 6.5% 7.9% 1.3%
Jerad Eickhoff 20.6% 20.5% -0.1% 7.6 8.3 0.7 0.278 0.328 0.050 5.2% 9.2% 4.0%
Jake Arrieta 23.9% 23.1% -0.8% 8.7 8.7 0.0 0.241 0.279 0.038 9.6% 7.8% -1.8%
Jake Odorizzi 21.5% 21.0% -0.4% 8.0 8.0 0.0 0.271 0.227 -0.045 7.0% 10.1% 3.1%
Tom Koehler 19.0% 18.6% -0.4% 7.5 7.7 0.2 0.298 0.313 0.015 10.7% 10.5% -0.2%
Marco Estrada 22.8% 21.8% -1.0% 8.4 8.5 0.1 0.234 0.295 0.061 9.0% 8.8% -0.2%
Sean Manaea 20.9% 20.2% -0.7% 7.7 7.9 0.2 0.281 0.318 0.037 6.2% 8.0% 1.7%
Clay Buchholz 15.8% 12.5% -3.3% 6.0 6.1 0.1 0.263 0.484 0.221 9.4% 7.5% -1.9%
Matt Andriese 20.7% 20.3% -0.4% 7.7 8.0 0.3 0.304 0.296 -0.008 4.7% 7.5% 2.8%
Mike Foltynewicz 21.1% 20.7% -0.5% 8.1 8.4 0.3 0.301 0.324 0.023 6.7% 8.5% 1.9%
Jordan Zimmermann 14.7% 14.5% -0.2% 5.6 5.8 0.2 0.304 0.330 0.026 5.8% 6.2% 0.4%
Tyler Wilson 13.3% 12.9% -0.4% 5.3 5.3 0.0 0.301 0.358 0.058 5.8% 5.7% -0.1%
Vance Worley 15.3% 15.0% -0.3% 5.8 6.3 0.5 0.281 0.378 0.097 9.6% 9.0% -0.6%
Fernando Salas 21.8% 21.3% -0.6% 7.8 8.6 0.8 0.258 0.337 0.080 6.5% 8.4% 1.9%
Alex Wilson 16.5% 16.2% -0.4% 6.0 6.3 0.3 0.285 0.311 0.026 7.1% 5.8% -1.3%
Michael Tonkin 25.4% 24.7% -0.7% 10.0 10.3 0.2 0.344 0.296 -0.047 7.6% 12.4% 4.8%
Mark Melancon 24.1% 22.3% -1.8% 8.2 8.7 0.5 0.259 0.374 0.114 4.4% 4.6% 0.2%
Cody Allen 33.0% 32.6% -0.3% 11.5 12.3 0.8 0.232 0.304 0.071 10.2% 7.5% -2.8%
Blake Treinen 24.0% 22.8% -1.2% 8.5 8.8 0.3 0.280 0.344 0.064 11.8% 7.7% -4.1%
John Axford 20.8% 19.3% -1.5% 8.2 9.0 0.8 0.311 0.364 0.053 10.4% 15.6% 5.2%
Trevor Cahill 23.2% 22.8% -0.4% 9.0 9.3 0.3 0.246 0.326 0.080 12.3% 11.8% -0.5%
Jim Johnson 25.6% 23.8% -1.7% 9.5 9.7 0.2 0.314 0.317 0.003 7.5% 9.8% 2.3%
Tyler Clippard 27.5% 27.3% -0.2% 10.3 10.7 0.5 0.288 0.248 -0.039 9.9% 11.7% 1.8%
Joe Musgrove 21.5% 21.2% -0.3% 8.0 8.1 0.1 0.289 0.315 0.026 6.3% 6.1% -0.2%
Kevin Siegrist 26.6% 25.0% -1.6% 9.6 9.8 0.2 0.221 0.337 0.116 10.5% 12.8% 2.3%
Matt Bush 25.1% 24.2% -0.9% 8.9 10.0 1.1 0.245 0.329 0.084 5.8% 7.9% 2.2%
Hunter Strickland 22.8% 21.6% -1.2% 8.4 8.5 0.1 0.274 0.314 0.040 7.6% 10.8% 3.2%
Jonathan Broxton 22.0% 20.5% -1.5% 8.5 9.2 0.7 0.268 0.429 0.161 9.3% 14.1% 4.8%
Jake Barrett 22.4% 21.5% -0.9% 8.5 8.7 0.2 0.261 0.274 0.013 11.2% 12.4% 1.2%
Vidal Nuno 20.7% 16.9% -3.8% 7.8 8.0 0.2 0.326 0.340 0.015 4.5% 13.0% 8.5%
Francisco Rodriguez 22.1% 19.5% -2.6% 8.0 8.2 0.1 0.252 0.297 0.046 8.9% 9.3% 0.4%
Jeremy Jeffress 17.4% 17.3% -0.1% 6.5 7.0 0.5 0.303 0.318 0.015 7.5% 11.5% 4.1%
Derek Law 23.4% 20.8% -2.5% 8.2 8.4 0.3 0.270 0.357 0.087 4.2% 8.3% 4.1%
Michael Lorenzen 23.8% 22.2% -1.6% 8.6 8.7 0.0 0.277 0.295 0.018 6.4% 9.4% 3.0%
Cory Gearrin 22.8% 22.5% -0.4% 8.4 8.5 0.1 0.286 0.263 -0.023 7.1% 12.3% 5.2%
Bruce Rondon 31.3% 29.0% -2.3% 11.1 12.6 1.5 0.228 0.476 0.248 8.3% 13.2% 4.8%
Brian Ellington 22.5% 21.9% -0.6% 8.7 9.7 0.9 0.278 0.333 0.056 11.3% 16.0% 4.7%
Jharel Cotton 20.5% 18.6% -2.0% 7.1 7.3 0.3 0.198 0.279 0.082 3.6% 9.4% 5.8%
Mike Bolsinger 20.5% 19.9% -0.6% 8.1 8.5 0.4 0.329 0.331 0.001 7.4% 13.8% 6.4%
Jose Valdez 22.0% 21.3% -0.7% 8.5 8.5 0.0 0.224 0.271 0.047 16.0% 6.3% -9.8%

Rick Porcello: I missed bad on Porcello this past season. I thought some late 2016 season changes were sustainable which could help him suppress his BABIP. I was wrong. His BABIP jumped 55 points as he could keep up his 2016 momentum.

His problems stem from his love for his two-seam fastball. He throws it about a third of the time and it generates a 45% GB% and just a 3.5% SwStr% which are way below the league average. He moved away from the pitch in late 2016 but went back throwing it in 2017 and his results were horrible.

Jake Arrieta and Jon Lester: I’m not surprised at all to see to Cubs pitchers on the list. After the team posted a historically low BABIP in 2016, it was due for some regression. Even the whole team had divergent strikeout rates.

Year: K%, K/9
2016: 24.3%, 8.88
2017: 23.6%, 8.95

Johnny Cueto: The 31-year-old got hit with both his BABIP and walk rate jumping. I used to like buying low on Cueto but several trends have me worried. His velocity is down the past three seasons. His Zone% dropped 4.5% points to a career-low 43%. He’s going to be tough to value going into next season.

Jerad Eickhoff: I’m also not sure how to value the 26-year-old going into next season. His ERA has jumped a point each year (2.65 to 3.65 to 4.71) and his walk rate nearly doubled (5.2% to 9.2%) this past season. Additionally, the flyball-heavy pitcher saw his BABIP go from .278 to .328. The 2017 struggles are likely from his two DL stints (back and then hand) so some 2018 rebound is possible.

Marco Estrada: The 60 point BABIP jump was too much to overcome to keep his ERA in check. Additionally, his season started out fine with a K/9 of 10.5 but it quickly fell. From 10.5 to 8.8 to 7.9 to 7.4 to 6.1 in September. While he didn’t miss any time with a known injury, something seemed wrong. He did drop his elite changeup usage 5% points but that shouldn’t explain all the struggles.





 

Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won four FSWA Awards including on for his Mining the News series. He's won Tout Wars three times, LABR twice, and got his first NFBC Main Event win in 2021. Follow him on Twitter @jeffwzimmerman.

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2017ammi
6 years ago

HIGHTLIGTS
INERT
IMPORTANT DEFINATION

-9