On Plate Discipline

Alex Wong

Spencer Schneier recently had a fantastic read on a new way to evaluate plate discipline. While his take is strong and worth the read I feel we can take it further. The basic concept of plate discipline is to take pitches out of the zone and to make contact on those within the zone. There's a lot more to hitting, but for these purposes we're going to keep this as simple as possible. With that in mind I've hastily thrown together a flow chart with good outcomes (green) and bad (red) to keep these ideas separate:

Extrapolating on this idea I want to propose a couple of metrics that we'll call Good Approach (GA) and Bad Approach (BA). GA will be defined as taking pitches out of the zone and swinging at pitches within the zone. Conversely, BA will be swinging at pitches out of the zone and taking those within the zone. Fangraphs makes it easy to pull this stuff using their plate discipline figures.

Of course, they don't just give it to you, you have to do a little bit of work. We can manipulate the data in the following way:

GA = OZone Takes + Zone Swings

GA = (1-Zone%)*(1-OSwing) + (Zone%*ZSwing)

BA = OZone Swings + Zone Takes

BA = (1-Zone%)*(OSwing) + (Zone%*(1-ZSwing))

Now that we have an idea of what terms we're talking about it becomes easier to manipulate the data. Here's a Google Drive link and find the tab "Approach". For now just pay attention to what we've already discussed. If we sort by GA you'll see that Moises Alou in 2002 had the best overall approach. He took 39% of pitches out of the zone and swung at 44% of pitches within the zone. On the season, Alou showed proper judgement on roughly 82% of all pitches thrown. There's some interesting names of guys on here, particularly Vlad Guerrero checking in very high. Vladdy was traditionally thought of as a hacker, but those extra swings also mean he's swinging at a lot of strikes. More than most batters as a ratio.

Let's take a look at the guys that displayed a bad approach. Martin Prado, just last year, can be more fairly described as passive than patient by this approach. His 39% take rate on pitches out of the zone is in the middle of the pack, but he's only swinging at 22% of pitches in the zone. That's one of the worst rates in the league and shows a batter that's not efficiently attacking good-to-hit pitches. Some other names on this end of the spectrum that do not surprise are J.J. Hardy, Alfonso Soriano, Mark Trumbo, and Jeff Francouer.

So it's one thing to swing at pitches in the zone and it's another to actually put those pitches in play. A whiff doen't help the offense even if it was on an easy to hit pitch. With that in mind I'd like to introduce Good Approach, Good Result (GAGR) and Bad Approach Bad Result (BABR). You can refer to the flow chart again, but basically we're adding ZContact into GA and (1-OContact) to factor in contact for pitches in the zone and whiffs for pitches out of the zone.

If you sort by GAGR you'll find Mr. Barry Bonds occupying the top-two spots and Moises Alou pops back up. These batters don't swing at pitches out of the zone as often as their peers, swing at many pitches in the zone, and when they do swing the make a ton of contact.

Sorting by BABR gives us Brett Gardner's 2010 as the worst approach with the worst results. The biggest reason for this is due to his study-worst 27% Zone Take rate which is something that you'll notice has him in common with most of these other guys at the top of this list, but it doesn't help that 21% of all pitches seen result in him making contact on a pitch in the zone. This is the definition of guys that are too passive taking too many hittable pitches.

I've also taken a look at this over longer than one season. In this Google Drive Link I've looked at qualified players over their entirety of time played from 2002 - 12. Again, we see that Moises Alou stands out for having the best approach with the best results. He either took a pitch outside of the zone or put a pitch in the zone in play 76% of his time over 3,000+ PAs. Here's the rest of the top-10 for those that didn't open the link:

Moises Alou 76%

Barry Bonds 75%

Bill Mueller 75%

Rey Sanchez 75%

Brian Giles 75%

Kenny Lofton 74%

J.T. Snow 74%

The other side of the coin shows this top-10 for BABR:

Todd Zeile 28%

Brett Gardner 28%

J.J. Hardy 27%

Dave Roberts 26%

Chris Snyder 26%

Luis Castillo 26%

To take this one, and final, step further we can use the weighted average mean and standard deviation for both GAGR and BABR to create standardized values. This will tell us how many standard deviations a player is from the mean. A high positive value for GAGR, like Moises Alou at 2.89, shows just how far from the norm his GAGR score is. The furthest out value in the other direction is Mark Trumbo at 3.47 deviations from the mean.

BABR works in the other direction with more negative being better and vice-versa. Nomar showed the best BABR score at 3.45 deviations from the norm edging out Pablo Sandoval. Meanwhile, Todd Zeile shows up again in the other direction at 3.05 deviations from the norm edging out Brett Gardner. We can combine these two standardizations (GAGR + (1-BABR) which you will find in the column labeled "Discipline." This way we're accounting for both GAGR and BABR. Here's your top-20:

Moises Alou 5.91

Nomar Garciaparra 5.85

Randall Simon 4.61

Magglio Ordonez 4.09

Barry Bonds 4.05

Chipper Jones 4.04

Rafael Palmeiro 4.01

Rey Sanchez 4.00

Mike Sweeney 3.77

Bill Mueller 3.73

Jeff Kent 3.61

Marcus Giles 3.57

J.T. Snow 3.49

Jeff Bagwell 3.48

Mark Kotsay 3.36

Ryan Klesko 3.35

Fred McGriff 3.31

Scott Spiezio 3.30

Luis Gonzalez 3.29

And here's the bottom-20:

Mark Trumbo -4.59

J.J. Hardy -4.48

Brett Gardner -4.41

Danny Valencia -4.39

Reed Johnson -4.23

Miguel Olivo -4.04

Jesus Flores -3.64

Alexi Casilla -3.59

Giancarlo Stanton -3.57

Franklin Guterrez -3.55

Todd Zeile -3.53

Sean Rodriguez -3.50

Chris Denorfia -3.50

Jonathan Lucroy -3.40

Jeff Mathis -3.37

Josh Wilson -3.34

Jamey Carroll -3.30

Chris Johnson -3.25

Elvis Andrus -3.19

Chris Snyder -3.18

Power can help make up for contact issues or passivity and that's something that I'd like to be able to incorporate into this thing, but for now, I think it makes a solid tool for analyzing whether a batter is showing good, bad, or indifferent plate discipline.

This post was written by a member of the DRaysBay community and does not necessarily express the views or opinions of DRaysBay staff.

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