Quantifying Plate Discipline

In my column this morning on Baseball Prospectus (subscription required but well worth it) among other things I take another crack at the PITCHf/x Gameday data. In part, inspired by this fascinating article, I created a couple of metrics to quantify plate discipline. They are:

Swing (S) defined as the percentage of pitches the batter swung at and also available in many other places. Obviously high values here are indicative of aggressive hitters or hitters who see a greater percentage of pitches out of the strike zone.

Fish (F) defined as the percentage of pitches out of the strike zone that the hitter swung at. A higher percentage here indicates that the hitter may have trouble recognizing pitches since he is offering at pitches that would likely otherwise be called balls. It should be noted that the strike zone as defined for this analysis is 17 inches wide (the standard) and uses the actual height customized for the player. No buffer room was added as was done in the previous articles since here we're not concerned with giving the umpire the benefit of the doubt.

Bad Ball (BB) defined as the percentage of pitches out of the strike zone that were swung at and made contact with (including foul balls although there is an argument to be made that a foul ball is not the intended outcome and so should be discounted in some way). A higher value in this category indicates that the hitter, when swinging at bad pitches, is at least able to get the bat on the ball.

Eye (E) defined as the percentage of pitches in the strike zone on non-three and zero counts that were taken for strikes. A smaller value in this metric indicates a player who recognizes strikes and aggressively offers at them. Non three and zero counts were excluded since obviously a hitter is much more likely to let a strike go by in this situation and so we don’t want to penalize them for that behavior. Some readers will see, however, where this idea could be extended to each of the eight possible counts and a system devised where less penalty is credited to hitters who take at 3-1 than those that do so at 0-2.

Without further ado here's the list (with the big caveat that only 24% of all pitches in 2007 have been tracked in the system and there is a heavy bias to the AL West because of the parks that the system is installed in) of all players who have 200 or more pitches tracked this season sorted by "Fish".

Name              Stand    Pitches   Swing    Fish BadBall     Eye
A.J. Pierzynski   L            357   0.602   0.469   0.813   0.117
Garret Anderson   L            260   0.515   0.467   0.750   0.350
Delmon Young      R            200   0.550   0.454   0.630   0.228
Rob Mackowiak     L            297   0.525   0.438   0.738   0.240
Hank Blalock      L            332   0.521   0.430   0.632   0.183
Erick Aybar       L            235   0.532   0.430   0.869   0.217
Carl Crawford     L            216   0.519   0.427   0.738   0.171
Jeffrey Francoeur R            337   0.546   0.425   0.775   0.094
Vladimir Guerrero R            403   0.524   0.421   0.771   0.142
Adrian Beltre     R            430   0.512   0.403   0.694   0.234
Michael Young     R            585   0.523   0.403   0.766   0.284
Eric Chavez       L            519   0.503   0.394   0.736   0.225
Kenji Jojima      R            270   0.522   0.389   0.878   0.217
Nomar Garciaparra R            436   0.557   0.388   0.800   0.132
Juan Pierre       L            431   0.480   0.385   0.916   0.302
Yuniesky BetancourR            345   0.496   0.383   0.806   0.279
Joe Crede         R            376   0.503   0.381   0.729   0.238
Jason Phillips    R            203   0.493   0.381   0.721   0.303
Vernon Wells      R            417   0.501   0.380   0.713   0.216
Jose Lopez        R            347   0.478   0.375   0.853   0.288
Ichiro Suzuki     L            515   0.435   0.369   0.862   0.326
Khalil Greene     R            407   0.514   0.367   0.595   0.247
Orlando Cabrera   R            517   0.468   0.362   0.838   0.279
Brian Mccann      L            267   0.434   0.358   0.783   0.282
Kevin Kouzmanoff  R            363   0.499   0.350   0.724   0.167
Lyle Overbay      L            381   0.465   0.349   0.704   0.230
Sammy Sosa        R            532   0.492   0.349   0.625   0.205
Royce Clayton     R            227   0.515   0.348   0.457   0.194
Adam Lind         L            336   0.482   0.348   0.719   0.253
Andruw Jones      R            389   0.478   0.344   0.686   0.232
Jose Guillen      R            394   0.475   0.344   0.636   0.232
Alexis Rios       R            413   0.426   0.343   0.735   0.351
Marcus Giles      R            452   0.511   0.341   0.674   0.211
Bobby Crosby      R            474   0.451   0.338   0.652   0.327
Casey Kotchman    L            463   0.434   0.338   0.814   0.285
Gary Matthews Jr. L            449   0.441   0.334   0.781   0.223
David Dejesus     L            209   0.445   0.333   0.816   0.340
Nelson Cruz       R            374   0.457   0.330   0.690   0.268
Andre Ethier      L            376   0.500   0.329   0.803   0.200
Jose Vidro        L            336   0.461   0.329   0.870   0.200
Juan Uribe        R            334   0.476   0.328   0.651   0.232
Raul Ibanez       L            474   0.456   0.328   0.760   0.229
Gerald Laird      R            484   0.459   0.326   0.698   0.290
Jason Kendall     R            405   0.432   0.325   0.870   0.373
Jermaine Dye      R            452   0.442   0.324   0.753   0.267
Mark Teahen       L            213   0.437   0.324   0.636   0.307
Adrian Gonzalez   L            590   0.453   0.322   0.767   0.225
Darin Erstad      L            372   0.398   0.318   0.797   0.413
Shea Hillenbrand  R            330   0.445   0.308   0.821   0.297
Brad Wilkerson    L            263   0.414   0.306   0.755   0.303
Paul Konerko      R            457   0.420   0.303   0.765   0.290
Richie Sexson     R            448   0.446   0.303   0.732   0.211
Mark Ellis        R            440   0.409   0.302   0.851   0.380
Mark Teixeira     L            501   0.399   0.302   0.657   0.276
Kenny Lofton      L            514   0.434   0.300   0.818   0.239
Travis Buck       L            377   0.416   0.300   0.662   0.255
Michael Napoli    R            346   0.419   0.299   0.683   0.322
Kelly Johnson     L            384   0.393   0.292   0.787   0.315
Josh Bard         L            283   0.470   0.292   0.878   0.177
Edgar Renteria    R            346   0.405   0.290   0.688   0.275
Jeff Kent         R            420   0.476   0.285   0.611   0.176
Ian Kinsler       R            591   0.423   0.280   0.784   0.268
Terrmel Sledge    L            285   0.446   0.272   0.609   0.217
Rafael Furcal     L            371   0.391   0.270   0.857   0.353
Shannon Stewart   R            437   0.410   0.269   0.810   0.327
B.J. Upton        R            225   0.431   0.269   0.528   0.227
Frank Thomas      R            478   0.377   0.267   0.838   0.335
Troy Glaus        R            306   0.376   0.264   0.706   0.330
Jose Cruz Jr.     L            285   0.428   0.262   0.591   0.216
Aaron Hill        R            417   0.415   0.253   0.729   0.302
Willie Harris     L            205   0.400   0.248   0.765   0.239
Russell Martin    R            506   0.401   0.241   0.757   0.290
Luis Gonzalez     L            428   0.395   0.236   0.889   0.256
Nick Swisher      L            384   0.365   0.232   0.559   0.307
Tadahito Iguchi   R            462   0.422   0.230   0.678   0.243
Frank Catalanotto L            309   0.372   0.228   0.821   0.319
Mike Cameron      R            539   0.399   0.224   0.569   0.237
Reggie Willits    L            274   0.328   0.219   0.818   0.455
Brian Giles       L            381   0.396   0.218   0.804   0.269
Jim Thome         L            330   0.358   0.203   0.545   0.239
Bobby Abreu       L            203   0.374   0.185   0.545   0.274
Jack Cust         L            294   0.310   0.175   0.563   0.342
Wilson Betemit    L            208   0.327   0.155   0.700   0.282
Dan Johnson       L            387   0.282   0.148   0.737   0.346

Of course the interesting thing is that you can then plot the Fish and Eye metrics on a graph and then split the graph into four quadrants. Each quadrant creates a little profile that can be used to characterize a hitter's plate discipline. Note that the bottom left is the sweet spot.