Were the World Series Balls Affecting Pitchers?

(Jake Roth / USA TODAY Sports)

by Jack Gioffre

The excitement of the 2017 postseason was marred by the comments from several pitchers regarding the condition of the baseballs they were using. Among them were former MVP Justin Verlander, Cy Young Award Winner Dallas Keuchel, Yu Darvish, and Charlie Morton. While Commissioner Rob Manfred insists nothing has changed with the production of the balls, the World Series record for home runs disagrees. The main complaint made concerned the slickness of the balls and the height of the seams. With a slicker ball and lower seams, the typical movement of breaking balls and the air resistance on fly balls decreases. The pitchers who commented on the baseballs use dominant breaking balls (with the exception of Verlander, who has a very good slider to accompany an overpowering fastball).

Yu Darvish, traded at the deadline to bolster the Dodgers’ already prolific rotation, had two lackluster starts in the World Series in which he gave up 8 ER in 3.1 IP. Due to these results, Darvish was quoted making comments about the slickness of the ball. Darvish relies mainly on his fastball and slider, which comprised 60.04% of his pitches in the regular season. The slider alone was thrown on 24.63% of pitches in the regular season, for a BAA of .173. In the postseason alone, Darvish threw his slider 29.90% of the time, even more than usual. Although the postseason is a very small sample size, opponents hit just .117 against it, for only 1 hit. So why is Darvish complaining about the balls when it appears he had success using his signature pitch? It is most likely because of the lack of movement he was having with his pitch. During the regular season, Darvish averaged around 8.8-9 inches of horizontal movement on his slider. In the postseason he maintained the same amount of horizontal movement, but suffered a significant change in vertical movement. Darvish typically averages between 1 and 2 inches of drop with his slider. However, in the playoffs, he actually experienced rise with his slider, an average of almost an inch. This makes for a total of 3 inches, the difference between a pitch at the bottom of the zone and one that creeps towards the middle. This could seem to be enough evidence to show that, for Darvish, something was affecting his pitches. In September Darvish experienced similar strife with his slider, not achieving the same amount of drop he had been the rest of the season. His September average of .24 inches of negative horizontal movement was well below his season average and was a preview of his struggles in October.

These numbers most likely contributed, but another possible factor would be his release point. For breaking pitches, and sliders in particular, a flatter release point equates to less spin, and thus less movement. Brian Bannister, the Red Sox VP and Head of Pitching Development tweeted during Game 3 of the World Series that Darvish’s release point was lower than normal. The Brooks data points to the same thing. In the regular season, Darvish’s vertical release point on his slider hovered around 5.6-5.7 feet off of the ground. In the postseason, his vertical release on the slider was much lower, at 5.2-5.3 feet high. These inches would create a different spin, giving Darvish less movement on his pitch and leaving balls in the zone instead of having them tail out of it. 


These two factors most likely combined in some degree to account for Darvish’s extremely poor performances. People forget that in Darvish’s two playoff performances with the Rangers he pitched to the tune of a 5.62 ERA, a number that looks pretty out of nowhere. It’s largely unclear from Darvish’s case what exactly caused his failures, but the ball remains a possibility.

Keuchel instead relies on an elusive sinker, which he threw for more than half of his pitches (51.08%). This, combined with heavy slider usage (18.37%), makes for a pitcher with an extremely interesting repertoire. Keuchel threw his fastball just 6.76% of the time in the regular season, an absurdly low amount. This statistic, combined with the rumors of slick balls affecting movement of breaking balls, seems to make for a difficult postseason for Keuchel. But, unlike Darvish, he performed relatively well in the World Series and postseason as a whole. He threw 27.2 innings for an ERA of 3.58: not the performance of a true ace but certainly an acceptable one.

In the postseason Keuchel threw his slider about as often as the regular season, but increased his cutter usage significantly. What is interesting about this is that his cutter actually moved more in the postseason, contradicting the comments swirling around the media. His cutter moved, on average, 1.98 inches in the postseason, up from .49 inches in the regular season. This increase in movement certainly explains his increased usage, but doesn’t align with the complaints registered by pitchers. Keuchel’s signature sinker didn’t experience a drastic difference in movement either, actually experiencing slightly more sink than usual. An anomaly that popped up again with Keuchel is that his September numbers on the movement of his pitches are drastically different from his normal numbers. The spike in his cutter movement begins in September and carries over into the postseason. We could again consider the implementation of these balls at the end of the regular season, but what this most likely points to is fatigue. Despite Keuchel’s injury, he still threw for almost 150 innings, and as the end of the season approaches it becomes harder to control pitches. Darvish went up to 186 innings, and towards the end of the regular season it was evident that he was struggling with command issues.

Verlander’s case is more interesting because, as a power pitcher, his reliance on breaking pitches is lesser than that of Keuchel. Verlander also possesses a slider and a power curve, which has the potential to lose movement with a slicker ball. Verlander typically uses 4 pitches: four-seam fastball, slider, curveball, and changeup. In the 2017 playoffs, he used almost exclusively his fastball and slider (88.01%). Verlander’s postseason performance was significantly better than both Keuchel’s and Darvish’s, with just one outing that could be argued as poor. All of Verlander’s postseason pitch measurements align fairly well with his regular season numbers, raising the question of why Verlander was complaining about the balls if his pitches weren’t losing effectiveness. Given his success, his endorsement of different baseballs might be the strongest. One could argue that Keuchel and Darvish are blaming the baseballs for their poor performances, but the same cannot be true for Verlander. Despite his success he is acknowledging the fact that the balls are slightly different, making his endorsement probably the most important.

It is easy to simply declare that the ball is juiced because it “feels” like there have been a lot of home runs this year. This was the case throughout both the regular season and the postseason, where records for both most home runs in a season and most home runs in a World Series were hit. This leads us to the conclusion that the balls were changed for the entire season, not just the World Series. If this was the case, Darvish, Keuchel, and others would be struggling for the entirety of the season, not just in the World Series. Yet a tweet of the World Series balls certainly gives the impression that they’re different, slicker.

postseason sliders

Tom Verducci, Sports Illustrated

The ball on the right, from the World Series, definitely appears slicker. A conflicting narrative between the Commissioner’s Office and the players leaves a lot up in the air. While some of the data points to an anomalous difference in statistics, others do not. It is uncertain if a definitive truth exists.

All data and statistics from Brooks Baseball

Categories: Analysis, Articles

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