Do long layoffs favor pitchers?

INTRODUCTION

Game One Friday night of the National League Division Series between the New York Mets and the Los Angeles Dodgers featured a premiere matchup between Jacob deGrom and Clayton Kershaw. Both pitchers performed splendidly, each recording double-digit strikeouts – deGrom, 13 and Kershaw, 11. This was the first time in postseason history that both starting pitchers recorded at least 11 strikeouts in a game. One thing of note during the game was how much harder deGrom was throwing the ball, especially early in the game.

TBS broadcaster Ron Darling, who covers the Mets for SNY on an everyday basis, noted the increased velocity and the pitcher’s duel prompted Mark Saxon of ESPN to write a short piece entitled, "Do long layoffs favor power pitchers?" Saturday, in which he showcased this matchup to support a conclusion that the long layoff in between the final game of the regular season and the first game of the postseason favors hard throwers like deGrom and Kershaw over the hitters. It was an interesting concept that seems to fall in line with the idea that hitters are likely to get rusty, and have their timing thrown off by the long layoff without playing every day .

Saxon includes quotes from hitters, most notably Justin Turner, that support the conclusion that the four-day layoff between the end of the regular season and the beginning of the Division Series favors hard-throwing pitchers. Here is what Turner had to say:

"The time off is always something that you think about, because hitting is all about having your timing and your rhythm at the plate. So, no matter what you do in those four days, you're not 100 percent sure if your timing is going to be there when you come back, especially running into guys that run it up there 95, 96, 97, 99 [mph]."

Other than this quote from Turner, Saxon does not offer anything in the way of evidence that his position is true. In this article I will use empirical data to see if in fact the long layoff does give all pitchers an unfair advantage, and through that research if power pitchers are affected in a different way than all pitchers in general.

METHODOLOGY

The population used in testing this hypothesis is relatively small – it contains all pitchers who started Game One of their respective team’s Divisional Series in the two Wild Card team era. That means that I only went back as far as 2013. Also, because Saxon’s support for his theory is that the hitters are affected negatively in their time off, I’ve eliminated pitchers who started against the teams who won their Wild Card games. These hitters did not have the same length of time off, therefore they don’t apply. For example, in 2015 Yordano Ventura’s Game One start against the Houston Astros is not counted because the Astros played in the Wild Card Game against the Yankees two days prior.

What resulted was the following table of starting pitchers. They represent 18 games started in total, 104.1 innings pitched and 443 batters faced. There is a fair amount of turnover on the list, although Clayton Kershaw appears three times, and Max Scherzer twice. The other 13 starting pitchers appear exactly once.

To test Saxon’s hypothesis, we are going to look mainly at two metrics: K% and BB%. Fastball velocity has been included as well – partly because Saxon brings it up in his article, and partly for fun.[1] This also comes with the added benefit later of parsing out the hard-throwers to further test Saxon’s hypothesis. The reason for looking at these stats is because they are 1. quicker to stabilize than any other pitching stats[2] and 2. more under control of the pitcher than other pitching stats.

If Saxon’s hypothesis is true, then what we should see in the data is an increase in K% and a decrease in BB% among the population.  All velocity data is pulled from Brooks Baseball, while the season strikeout and walk rates were pulled from FanGraphs. The single-game strikeout and walk rates were calculated using the box scores of the games.

EFFECT OF LAYOFF ON STRIKEOUT RATE

If the layoff is really an advantage for pitchers because hitters' timing is off, logic indicates that pitchers should be able to strike out far more hitters than normal. If a hitter’s timing is off, not only is hand-eye coordination compromised, but so will contact rates and the ability to recognize pitches quickly. All of this should contribute to higher than normal strikeout rates.

There is quite the range there, going from deGrom adding 20.8 percentage points, to A.J. Burnett losing 26.1 percentage points in their playoff starts. As a whole, the group does not in fact strike out a higher rate of batters. The difference is almost negligible among the entire group – only a -0.18 percentage point difference on average. Saxon’s hypothesis appears to be on thin ice. However, let’s see how hard-throwers fare. For the purposes of this experiment and for the rest of the article, hard-throwers will be defined as a pitcher who averages at least 93.0 mph on his fastball.

Isolating only those pitchers categorized as hard-throwing, we see the strikeout rate improves by an average of 1.65 percentage points.[3] This is a step in the right direction of validating Saxon’s hypothesis, as at least there is a positive trend. However, the standard deviation for strikeout percentage among a population of all qualified starting pitchers from 2013 to 2015 was 4.22 percentage points. The difference in strikeout rate, even among hard-throwers is not even close to statistically significant change, and is right in line with how we might expect those pitchers to perform in normal circumstances.

EFFECT OF LAYOFF ON WALK RATE

Again, if a hitter’s timing is off, and his ability to quickly recognize pitches is compromised, it can be deduced that it would be harder to walk this batter. While this is all speculation, let’s see if it rings true in the data.

What we see for all pitchers is actually the opposite of what we would expect if pitchers held a true advantage because of an extended playoff layoff.[4] But a 0.59 percentage point difference is again basically nothing. Let’s isolate the hard-throwers and see what the results are.

Like with strikeout rate, we see a larger split with the hard-throwing pitchers, but in the opposite direction! Hard-throwing pitchers actually walk more batters than the general population, although it only differs by slightly less than one standard deviation.[5] The increase in walks among pitchers is not significant.

CONCLUSION

It would be nice if we had a larger population to work from to test Saxon’s hypothesis that long layoffs between the regular season and the start of the playoffs favor power pitchers, and the more general hypothesis the same layoffs favor pitchers in general. As the years go by under the current playoff system, and we have more data we can revisit the topic with more certainty. I am still confident with the given data to say that there is no measurable advantage for pitchers over hitters after a long layoff. Saxon’s hypothesis, while certainly logical, is not supported by the empirical evidence gathered here. By the same token there is no measurable advantage for hitters, and we should expect individuals to perform as they regularly would.