# Introducing: The Maddux Plate Discipline Index (mPDI) for Pitchers

“The key to pitching is to have the ability to throw a strike when they’re taking and throw a ball when the hitter is swinging.”Greg Maddux

Last week, I introduced a pitcher metric based on the six possible plate discipline outcomes. You can find the definitions and indexes in the wPDI introduction article, found here.

This week, I would like to provide you with an alternative weighting of the indexes. It will parallel the famous quote by Hall of Fame pitcher, Greg Maddux. He preached that the key to pitching is to throw a strike when the batter isn’t going to swing, and to throw a ball when the batter will [swing].

With the wPDI outcome framework in place, we can now properly quantify Greg Maddux’s quote.

Here is a quick reminder on what the six possible plate discipline outcomes look like:

Classifying the 6 Pitching Outcomes
Outcome Outcome Outcome Outcome Outcome Outcome
A B C D E F
Zone? Out of Zone Out of Zone Out of Zone In Zone In Zone In Zone
Swing? Swung On Swung On No Swing Swung On Swung On No Swing
Contact? No Contact Contact Made No Swing No Contact Contact Made No Swing

Maddux Plate Discipline Index (mPDI) for Pitchers:

The formula for mPDI, the Maddux Plate Discipline Index:

mPDI = IndexA * A% + IndexB * B% + IndexC * C% + IndexD * D% + IndexE * E% + IndexF * F%

A%, B%, …, F% is defined exactly as in wPDI – the percentage of total pitches per each outcome.

The mPDI indexes are given as:

Pitching Outcome Indexes for mPDI
Outcome Description Index
A Out of Zone / Swung On / No Contact 100%
B Out of Zone / Swung On / Contact Made 100%
C Out of Zone / No Swing 0%
D In Zone / Swung On / No Contact 0%
E In Zone / Swung On / Contact Made 0%
F In Zone / No Swing 100%

Since the indexes for A, B, F are all 100%, and with C, D, E% all set to 0% – we can simplify the Maddux Plate Discipline Index (mPDI) as:

mPDI = A% + B% + F%

There we have it! This formula exemplifies Maddux’s key to pitching as the aggregate of three simple quantities. It represents the total percentage of outcomes where the batter either swings at a “ball” [Outcomes A & B] or looks at a “strike” [Outcome F]. We obviously know that pitching is a bit more complicated, but it’s a marvel to quantify a legend’s words.

mPDI tops out at around .400 for the elite, and bottoms out at roughly .200. The average for mPDI is lower than that of wPDI and comes close to .300. That is, roughly 30% of the time – pitchers are implementing Maddux’s key to pitching.

Let’s see the 2018 leaderboards for mPDI:

Name IP mPDI
Patrick Corbin 200.0 .372
Kyle Hendricks 199.0 .368
Chris Sale 158.0 .368
Zack Greinke 207.7 .360
Marco Gonzales 166.7 .357
Domingo German 85.7 .353
Collin McHugh 72.3 .352
Jason Vargas 92.0 .352
Jacob deGrom 217.0 .349
Carlos Carrasco 192.0 .349
Masahiro Tanaka 156.0 .347
Corey Kluber 215.0 .347
Felix Pena 92.7 .346
Alex Wood 151.7 .345
Pablo Lopez 58.7 .344
Aaron Nola 212.3 .344
Brett Anderson 80.3 .342
Lance McCullers Jr. 128.3 .341
Miles Mikolas 200.7 .340
Zack Godley 178.3 .339
Blake Snell 180.7 .338
Noah Syndergaard 154.3 .338
Stephen Strasburg 130.0 .338
Jakob Junis 177.0 .337
Dallas Keuchel 204.7 .336
Jeremy Hellickson 91.3 .336
CC Sabathia 153.0 .335
Joe Musgrove 115.3 .335
Bartolo Colon 146.3 .335
Trevor Bauer 175.3 .334
Hyun-Jin Ryu 82.3 .334
Shane Bieber 114.7 .334
Ross Stripling 122.0 .334
Jake Arrieta 172.7 .333
Carlos Martinez 118.7 .332
Ryan Borucki 97.7 .331
Jameson Taillon 191.0 .331
Alex Cobb 152.3 .331
James Paxton 160.3 .331
Rich Hill 132.7 .330
Jose Berrios 192.3 .330
Max Scherzer 220.7 .330
Justin Verlander 214.0 .330
Walker Buehler 137.3 .330
Doug Fister 66.0 .330
Tyson Ross 149.7 .329
Chris Archer 148.3 .329
Anibal Sanchez 136.7 .329
Mike Leake 185.7 .329
Trevor Cahill 110.0 .329
Andrew Heaney 180.0 .329
Brent Suter 101.3 .328
Zack Wheeler 182.3 .328
Minimum 35 IP

Patrick Corbin leaps over Chris Sale to sit atop the starting pitcher mPDI leaderboard. As previously noted, Corbin excels at outcome A – generating swings and misses out of the zone.

Kyle Hendricks now jumps up to the #2 spot due to his elite F outcome – he generates few swings within the zone. 19% of his pitches fall into this category.

Southpaw Marco Gonzales leapfrogs up to the #5 slot. He excels at outcome B – getting batters to make contact out of the zone.

Jason Vargas ahead of Jacob deGrom? Do the Mets have something special with their 5th starter?

2018 mPDI – Vargas vs. deGrom
Player Outcome A Outcome B Outcome F mPDI
Jason Vargas .072 .123 .157 .352
Jacob deGrom .089 .121 .139 .349

According to mPDI, in 2018 Vargas had fantastic plate discipline in the Maddux categories. Vargas did a better job than deGrom at pitching in the zone without generating a swing. While the overall out-of-zone metrics were in deGrom’s favor – Vargas fared a shade better at initiating the out-of-zone contact.

Name IP mPDI
Blake Treinen 80.3 .387
Ryan Pressly 71.0 .385
Will Smith 53.0 .384
Alex Claudio 68.3 .380
Oliver Perez 32.3 .378
Jace Fry 51.3 .378
Dellin Betances 66.7 .377
Dan Otero 58.7 .375
Craig Stammen 79.0 .371
JT Chargois 32.3 .369
Pedro Strop 59.7 .366
Taylor Rogers 68.3 .361
Alec Mills 18.0 .360
Will Harris 56.7 .359
Tyler Duffey 25.0 .358
Pat Neshek 24.3 .357
Erik Goeddel 36.7 .357
Tony Barnette 26.3 .356
Jared Hughes 78.7 .355
Daniel Coulombe 23.7 .355
Aroldis Chapman 51.3 .353
Aaron Loup 39.7 .353
Jeanmar Gomez 25.0 .352
Keynan Middleton 17.7 .350
Dylan Floro 64.0 .350
Steve Cishek 70.3 .350
Bud Norris 57.7 .349
Luis Santos 20.0 .348
Ryan Brasier 33.7 .346
Victor Alcantara 30.0 .345
Tommy Hunter 64.0 .345
Jeremy Jeffress 76.7 .344
Luis Cessa 44.7 .343
Keone Kela 52.0 .343
Kirby Yates 63.0 .343
Luis Avilan 45.3 .343
A.J. Cole 48.3 .342
Jose Alvarez 63.0 .342
Reyes Moronta 65.0 .342
Brooks Pounders 15.3 .341
Roberto Osuna 38.0 .341
Jake Diekman 53.3 .341
Trevor Hildenberger 73.0 .341
Minimum 15 IP

On the reliever side, not a whole lot has changed when going from wPDI (with my prior indexes) to mPDI. Aroldis Chapman moves down a bit – he excelled at outcome E, which isn’t factored in as much with the mPDI weights. Ryan Pressly, who I talk about here, also dazzles.

Alex Claudio is one reliever that caught my eye. Claudio excels at the A & B outcomes – the out-of-zone pitches. It seems that mPDI may have a small tilt towards lefties, as we have seen several of them bubble up to the top.

Below are the players with the largest gaps between mPDI and wPDI:

Largest mPDI vs. wPDI for 2018
Name IP mPDI wPDI mPDI – wPDI
Dan Otero 58.7 .375 .344 +.031
Bartolo Colon 146.3 .335 .309 +.025
Doug Fister 66.0 .330 .310 +.020
Alex Wilson 61.7 .339 .320 +.019
Brett Anderson 80.3 .342 .323 +.018
Eddie Butler 49.7 .309 .290 +.018
Mike Leake 185.7 .329 .311 +.018
Alex Claudio 68.3 .380 .363 +.017
Alex Cobb 152.3 .331 .317 +.014
Chris Volstad 47.3 .318 .304 +.014
T.J. McFarland 72.0 .316 .302 +.014
Ryan Borucki 97.7 .331 .319 +.013
Dallas Keuchel 204.7 .336 .323 +.013
Ty Blach 118.7 .327 .314 +.013
Joe Smith 45.7 .340 .329 +.012
Matt Koch 86.7 .310 .299 +.012
Marco Gonzales 166.7 .357 .346 +.011
Ariel Jurado 54.7 .269 .258 +.011
Kyle Hendricks 199.0 .368 .358 +.010
Minimum 35 IP

Bartolo!!!

Bartolo Colon (still active) throws a ton of strikes. It always amazed me that batters let so many of his pitches go by without a swing … knowing that so many pitches were simply mid-80 MPH fastballs in the zone.

Here are the players that dropped the most when switching to the Maddux indexes:

Largest wPDI vs. mPDI for 2018
Name IP mPDI wPDI mPDI – wPDI
Josh Hader 81.3 .297 .373 -.076
Emilio Pagan 62.0 .268 .325 -.056
Hector Neris 47.7 .322 .378 -.056
Sean Doolittle 45.0 .305 .357 -.052
Kazuhisa Makita 35.0 .282 .332 -.050
Jose Leclerc 57.7 .321 .370 -.049
Edwin Diaz 73.3 .332 .380 -.048
Seranthony Dominguez 58.0 .307 .354 -.046
Felipe Vazquez 70.0 .285 .330 -.046
Corey Knebel 55.3 .297 .342 -.045
Shohei Ohtani 51.7 .301 .346 -.044
Hansel Robles 56.0 .263 .307 -.043
Jerry Blevins 42.7 .252 .296 -.043
Daniel Hudson 46.0 .281 .323 -.042
Pedro Baez 56.3 .293 .334 -.040
Ryne Stanek 66.3 .302 .341 -.039
Chad Green 75.7 .288 .327 -.039
Joakim Soria 60.7 .305 .344 -.039
Minimum 35 IP

This list contains a large number of hard throwing relief pitchers. Hader’s best asset is his category D outcome. It is a swinging strike in the zone. Hader has more than double the major league average D outcome – which factors greatly for wPDI, but not for mPDI. Hader gets almost as many swings and misses in the zone as he gets called strikes in the zone. Interestingly and somewhat surprisingly, Hader’s mPDI is below average at .297. Edwin Diaz though (another elite reliever), still has a fantastic mPDI at .332.

Hader isn’t a mediocre pitcher. It is quite the opposite – he is elite. Hader’s plate discipline skills are just not what Greg Maddux had in mind.

Ariel is the 2019 FSWA Baseball Writer of the Year. Ariel is also the winner of the 2020 FSWA Baseball Article of the Year award. He is the creator of the ATC (Average Total Cost) Projection System. Ariel was ranked by FantasyPros as the #1 fantasy baseball expert in 2019. His ATC Projections were ranked as the #1 most accurate projection system in 2019. Ariel also writes for CBS Sports, SportsLine, RotoBaller, and is the host of the Beat the Shift Podcast (@Beat_Shift_Pod). Ariel is a member of the inaugural Tout Wars Draft & Hold league, a member of the inaugural Mixed LABR Auction league and plays high stakes contests in the NFBC. Ariel is the 2020 Tout Wars Head to Head League Champion. Ariel Cohen is a fellow of the Casualty Actuarial Society (CAS) and the Society of Actuaries (SOA). He is a Vice President of Risk Management for a large international insurance and reinsurance company. Follow Ariel on Twitter at @ATCNY.

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