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Fun With Numbers

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As you should all know by now, Fangraphs presents certain plate discipline statistics such as first strike percentage and swing rate on balls out of the strike zone. I don't know why it never dawned on me before, but just now I decided to convert these numbers into expected strike rate for pitchers and then compare the result to actual strike rate to see who's getting calls, and who's getting it in the shorts.

The calculation is pretty simple:

Pitches * Zone% = total # of pitches in the zone

Pitches - (pitches * Zone%) = total # of pitches out of the zone

Total # of pitches out of the zone * O-Swing% = total # of swings on pitches out of the zone

Total # of O-swings + Total # of pitches in the zone = Expected # of strikes

Strikes - expStrikes = Difference

Difference / Pitches = Difference%

Here are the leaderboards for pitchers with a minimum of 500 pitches thrown:

Top 10
Rank Pitcher Difference
1 J.D. Martin 4.6%
2 Jake Peavy 3.0%
3 J.P. Howell 3.0%
4 Max Scherzer 2.8%
5 Darren O'Day 2.8%
6 Brian Moehler 2.7%
7 Derek Lowe 2.6%
8 Javier Vazquez 2.5%
9 Jamie Moyer 2.4%
10 Darren Oliver 2.3%

In other words, JD Martin's strike rate is 4.6% higher than we'd expect it to be based on the number of pitches he throws in the zone and the number of swings he gets on pitches out of the zone.

Bottom 10
Rank Pitcher Difference
1 Evan Meek -3.6%
2 Carlos Villanueva -3.1%
3 Anibal Sanchez -2.9%
4 Ronald Belisario -2.7%
5 Luke French -2.7%
6 Jason Motte -2.7%
7 Mark DiFelice -2.7%
8 J.J. Putz -2.6%
9 Roman Colon -2.5%
10 Jose Valverde -2.4%

Evan Meek, meanwhile, has a strike rate that's 3.6% below where we'd expect it to be. Luke French makes the list as well, ranking 5th-lowest out of 382 pitchers.

(Note that there's a league-wide error of just under 0.4% - there have been 341,240 strikes against 339,264 expected strikes over 547,023 total pitches. This is corrected for.)

We've complained about Doug Fister getting jobbed on several occasions, and indeed, the numbers bear it out - he's registered 192 strikes and 203 expected strikes over three starts and four appearances, for a difference of -3.9%. That's the worst rate in baseball among guys who've thrown 300 pitches.

Anyway, for the curious, here's a link to the player spreadsheet, and here's a link to the team spreadsheet. By this method, the Braves have gotten the most calls, while the Brewers have gotten the least.