Some Samples No Longer Small: Pitchers
Twins Video
Sample sizes for a few ratios are becoming large enough to consider. For pitchers, strike out rate stabilizes at 70 batters faced and ground ball and fly ball rate stabilizes at 70 balls in play. By stabilizing, that doesn’t necessarily mean it is the new expected rate. It does mean that any significant changes from previous year cannot be written off to small sample size. For minor leaguers a drop or change likely coincides with a step up in classification and the necessary adjustment. It is also important to note that the 70 is a major league threshold. I am not aware of minor league research in this area. It is reasonable to assume that k-rate and ground ball rate would stabilize earlier than other rates.
Looking at the levels
[TABLE=class: grid, width: 564]
MinnesotaAgeTeamBF 2014K%
2013K%
2014GB%
2013GB%
Ricky Nolasco31.5MIN13410%20%50%41%Kyle Gibson26.7MIN12912%18%51%51%Kevin Correia33.8MIN12510%13%42%42%Phil Hughes28MIN12122%19%31%30%Mike Pelfrey30.4MIN1198%15%42%44%Samuel Deduno30.9MIN8322%16%49%58%Anthony Swarzak28.8MIN6910%18%46%44%[/TABLE]
A lot has been written about Pelfrey. The 8% strike out rate won’t cut it. Nolasco has a significant drop in strike out rate. A little of the drop can be attributed to switching leagues. His pitch mix in his early starts was very different than with the Dodgers. He was throwing more 4 seam fastballs and fewer sliders with the Twins. Maybe the Twins staff took notice. Yesterday’s game was the first Twin start in which he threw more sliders than 4-seam fastballs.
[TABLE=class: grid, width: 565]
RochesterAgeTeamBF 2014K%
2013K%
2014GB%
2013GB%
Kris Johnson29.7ROC/MIN113[/TD]22%17%50%50%Alex Meyer24.4ROC11231%30%41%57%Scott Diamond27.9ROC10513%10%35%45%Trevor May24.8ROC9632%24%33%38%Logan Darnell25.3ROC8824%19%41%49%Yohan Pino30.5ROC8532%22%[TD]30%
35%[/TABLE]
Meyer, May and Pino haven’t hit the 70 ball in play threshold for groundball rate to be stabilized due to their high strike out counts. I am looking forward to seeing May and Meyer in the majors. May’s mix may be similar to Phil Hughes and perhaps Target field will be a good match for him.
[TABLE=class: grid, width: 564]
New BritainAgeTeamBF 2014K%
2013K%
2014GB%
2013GB%
Taylor Rogers23.5NBR11722%16%42%53%Pat Dean25.1NBR11318%12%44%40%Sean Gilmartin24.1NBR9923%18%31%38%D.J. Baxendale23.5NBR9313%18%47%33%Matt Summers24.8NBR7617%17%53%44%[/TABLE]
Gilmartin’s rate should be followed. The increase could be explained by the drop from AAA to AA. It may also be a return to when he was seen as a good prospect. At some point, he will hit AAA and hopefully the improved strike out rate will follow him.
[TABLE=class: grid, width: 564]
Fort MyersAgeTeamBF 2014K%
2013K%
2014GB%
2013GB%
Tyler Duffey23.5FTM/NB11915%18%35%44%Jose Berrios20.1FTM11418%22%39%41%Mason Melotakis23FTM9419%18%50%46%Alex Wimmers25.6FTM8116%23%45%26%Steven Gruver25FTM7414%23%54%50%Tim Shibuya24.8FTM7013%17%69%48%[/TABLE]
I would expect Berrios’ numbers to improve as he adjusts to high A. Wimmers hasn’t pitched much either year. Let’s hope he can find the talent that made him a late first round pick.
[TABLE=class: grid, width: 564]
Cedar RapidsAgeTeamBF 2014K%
2013K%
2014GB%
2013GB%
Aaron Slegers21.8CR11623%27%61%60%Ryan Eades22.5CR11421%19%31%48%Kohl Stewart19.7CR9817%29%49%43%Felix Jorge20.4CR8217%29%37%48%Ethan Mildren23CR7225%19%65%51%Josue Montanez22.4CR7027%14%37%42%[/TABLE]
Sleger’s combination of strike outs and ground balls is encouraging. A midseason call up to Fort Myers seems reasonable.
Walk rate stabilizes next for pitchers at 170 plate appearances. I have looked for when pitch level data rates (swing and miss rate) stabilizes, but have not seen it. Since there are more pitch events than batters faced or balls in play events, I would guess that some of those rates have stabilized.


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