August 28, 2014

Statistically Speaking: A Tale of Two Strike Zones

In terms of the offense, how Ian Desmond and Jayson Werth go, the Nationals go. Both are productively dynamic hitters that approach their time in the batter’s box in very different ways.

For Desmond, it’s an aggressive plate discipline that paces the shortstop’s offense, with every first pitch of a plate appearance one that simply cannot be passed up. For Werth, it’s the exact opposite; there are very few pitches that are worthy of putting a swing on, as evidenced by his career 4.39 pitches seen per plate appearance average. To compare, Desmond has a career 3.59 pitches per plate appearance average.

With these disparate approaches to hitting, you would think that pitchers would have a different methods of getting each player out—for Desmond’s aggressive, undiscerning approach, getting him to chase pitches just out of the strike zone and for Werth, a more balanced plan of attack with more pitches in the strike zone to counter his discerning eye—and those potentially opposing approach would show up in their respective PITCHf/x data.

Using the aforementioned PITCHf/x data, we can determine how Desmond and Werth have been pitched, either with the pitcher avoiding the strike zone or by attacking the hitter and throwing pitches that get a lot of the zone, with little fear that they will put a good swing on a given pitch.

A recent article has shown that how close and how often a pitcher throws pitches to the strike zone can help identify breakout and breakdown candidates, with the greater distances indicative of a pitcher wanting to work around a hitter and not get beat by them and smaller distances from the zone showing a possible lack of respect of a hitter’s ability to turn on a strike.

For our purposes, I calculated distances from the center of the strike zone by applying the distance formula to the px and pz variables of each pitch:

distance equation, Pythagorean theorem

…with the center of the strike zone estimated using the average strike zone location, referenced here.

The distances (labeled ‘xy’) were plotted against the chronological order in which the pitch was seen over the course of the 2014 season; scatter plots were also created for each pitch type seen, with all fastball types collapsed into on category and the usual offspeed and breaking pitch type categorized separately.

The results:

Screen Shot 2014-07-01 at 10.34.26 PM
Screen Shot 2014-07-01 at 10.35.01 PM

Here, we find some interesting deviations between the two hitters. For Desmond, there is an overall slight downturn in the distance from the center of the strike zone on the pitches he’s seeing as of late, alluding to some potential breakdown in productivity. This is especially the case with the fastballs he has seen, with some of the uptick in zone distance seen in secondary pitches indicative of pitchers wanting Desmond to chase.

For Werth, the overall trend opposes Desmond’s with pitchers less likely to give him anything close to the plate to hit. Looking at the trend across pitch types, we see very subtle downticks in distance form teh zone in sliders and changeups, possibly a ramification of Werth’s reputation as a hitter with a very keen eye and pitchers aware that he is unlikely to chase soft stuff out of the zone.

A breakdown of the average zone distances for each pitch type for both hitters is as follows:

Player Pitch Avg Distance from Zone (ft.)
Desmond CH 1.263348
Desmond CU 1.318966
Desmond FA 1.067716
Desmond SL 1.269305
Werth CH 1.306862
Werth CU 1.408313
Werth FA 1.022414
Werth SL 1.219673

Again, very subtle differences are seen, but when extrapolated out, the differences can be vast. While there are a number of factors playing a role in how each hitter is pitched to and the interpretation of the very minute fluctuations in where pitches are ending up in reference to the strike zone, it is an interesting example of how despite both being notoriously streaky hitters, the more discerning eye of Werth has possibly prevented him from suffering from any extended slumps thus far this season. It is also a tacit revelation that in many instances, it’s the pitcher who will be the first to tell you how well you’re hitting.

Data courtesy of Baseball Savant.

Stuart Wallace is a Contributor to District Sports Page. A neuroscientist by day, the Nevada native also moonlights as an Associate Managing Editor for Beyond the Box Score, stats intern at Baseball Prospectus, and a contributor at Camden Depot. A former pitcher, his brief career is sadly highlighted by giving up a lot of home runs to former National Johnny Estrada. You can follow him on Twitter @TClippardsSpecs.

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