Some Samples No Longer Small: Pitchers

Sample sizes for a few ratios are becoming large enough to consider as reliable. For pitchers, strikeout rate stabilizes at 70 batters faced (BF) and ground ball and fly ball rates stabilize 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 due to small sample size.

For minor leaguers a drop or change likely coincides with a change in level of minor league and the necessary adjustment. It is also important to note that 70 is a major league threshold. I am not aware of minor league research in this area. It is perhaps reasonable to assume that K-rate (K%) and ground ball rate (GB%) stabilize earlier than other rates.

Looking at the levels:

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K%

K%

GB%

GB%

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A lot has been written about Pelfrey. The 8% strike out rate won’t cut it. Nolasco has seen a significant drop in strikeout rate. A little of the drop can be attributed to switching leagues. His pitch mix in his early starts was very different than when with the Dodgers. With the Twins, he was throwing more 4 seam fastballs and fewer sliders. Maybe the Twins staff took notice: yesterday’s game was the first Twin start in which he threw more sliders than 4-seam fastballs.

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K%

K%

GB%

GB%

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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.

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K%

K%

GB%

GB%

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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 where he was 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.

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K%

K%

GB%

GB%

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I 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.

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K%

K%

GB%

GB%

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Sleger’s combination of strikeouts 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 data rates (swing and miss rate and others) stabilize, but have not seen it. Since there are more pitch events (number of pitches) than batters faced events or ball in play events, I would guess that some of those rates have stabilized.