MLB Might Have Another New Ball and Controversy

HOUSTON — The investigative team of Ben Lindbergh, Rob Arthur and Alan Nathan might have to get back to work. Not only has the ball played differently since 2015 when it became livelier, now the World Series ball is playing differently players told Sports Illustrated’s Tom Verducci.

Lance McCullers took the blindfold test in the bullpen,” said Charlie Morton, Houston’s Game 4 starter, referring to another Astros pitcher. “He could tell which ball was which with his eyes closed. It’s that different.”

Said Houston pitcher Justin Verlander, “The World Series ball is slicker. No doubt. I’m telling you, we’re in here signing [World Series] balls before the game, and it’s hard to get the ink on the ball sometimes. You know when you sign a receipt at Starbucks, and if you don’t hold the paper down with your hand, the pen just slides across the paper and the ink doesn’t stick to it? That’s what it’s like sometimes trying to sign these balls. That’s how slick the leather is.

A slick ball is thought to negatively impact the slider more than other pitches since there is more contact between the grip hand and the surface of the ball. In throwing curveballs, for instance, pitchers typically dig into a seam.

Perhaps it is this slicker ball that led to, or played a role in, Darvish’s struggles with the slider in Game 3. Perhaps it is the latest new ball that explains some of Ken Giles’ on-going issues, and Brad Peacock’s decision to shelve his often-used slider in Game 3.

Moving forward in the series, a slicker ball would appear to be more of an issue for the Astros, which threw the fifth highest rate of sliders in the majors (20%), while the Dodgers ranked 18th (15.5%). But Game 5 starter Clayton Kershaw threw his slider at a career-high rate of 34.9% in the regular season, while Astros starter Dallas Keuchel relies less upon his breaking ball. More intrigue!

So is there a measurable change?

Let’s start with Kershaw. According to Brooks Baseball data, which I will use in this post, Kershaw’s slider averaged 5.68 inches of vertical movement and -2.06 inches of horizontal movement in the regular season. In his World Series Game 1 start? It averaged 5.99 inches and -1.46 inches, respectively. Kershaw did not shy away from the pitch in Game 1, he threw 32 sliders among his 83 pitches overall. The pitch generated six swings and misses and five balls in play, which averaged 81.1 mph in exit velocity, the weakest contact among his pitches according to Baseball Savant data.

And Yu Darvish, who struggled in Game 3, and who throws a slider on about a quarter of his offering (24% in the regular season)?

Darvish lost his slider in Game 3. He threw 14 of them and none generated a whiff. The pitch seemed to flatten and stay up in the zone.

Said Darvish to Sports Illustrated: “I had trouble with the ball throwing a slider. It was slicker.”

Darvish’s slider average 9.12 inches of horizontal movement in the regular season. In Game 3? 8.23 inches. Darvish’s vertical movement on his slider had been changing each month since joining the Dodgers, reaching -0.24 vertical in September. In the World Series? 0.30 inches. Really, not too much change as far as movement, but there were perhaps mechanics matters, and feel, at play in his poor Game 3 start.

Another slider-heavy pitcher who has struggled in the Series? Ken Giles.

Said Giles to reporters after his Game 4 ninth-inning blow up: “They were all crappy pitches.”

That is candid and concise. And Giles was fastball-heavy in Game 4:

In the World Series, Giles has had 1.89 inches of vertical movement on his slider. In the regular season? 1.07 inches. In the World Series, Giles has had -0.88 inches of horizontal movement. In the regular season? -0.03. Giles’ slider is not notable for its movement, rather for its velocity (87.3 mph). But the pitch is moving slightly differently in the postseason.

What is perhaps more notable with Giles is that his location has faltered and his velocity is down a full mph in the World Series.

Another slider-heavy Astros reliever, Peacock, abandoned the pitch in his tandem, piggy-back outing in Game 3.

Peacock’s slider averaged 5.86 inches of horizontal of movement in the regular season and the pitch has averaged 4.52 inches of vertical movement in the World Series, albeit a small sample of nine pitches.

The pitch averaged 3.61 inches of vertical movement in the regular season, and 5.72 inches of movement in the World Series.

Again, a really small sample, but Peacock’s slider is performing dramatically different, and Peacock abandoned it for a reason.

Kenley Jansen has inexplicably allowed runs and home runs in two World Series appearances. Jansen’s cutter averaged 9.37 inches of vertical movement and 3.25 inches of horizontal movement in the regular season. In the World Series? Jansen’s vertical movement has dropped to 8.99 inches and his horizontal movement has increased to 3.77

Jansen’s slider averaged -1.14 inches of vertical movement (-1.39 in the regular season) and 4.19 inches of horizontal movement in the World Series (3.21 inches of movement in regular season).

From a spin-rate perspective, it’s tough to identify anything meaningful in the following chart:

How are the Slicker balls Spinning?
Player Reg. season sliders Avg. RPM regular season WS sliders Avg. RPM World Series
Brad Peacock 589 2660 9 2624
Justin Verlander 759 2526 16 2649
Joe Musgrove 456 2484 3 2562
Ken Giles 436 2402 12 2392
Kenta Maeda 480 2401 12 2502
Ross Stripling 394 2347 9 2333
Dodgers as team 3190 2415 91 2508
Astros as team 4332 2439 62 2473

There’s already been much controversy since the second half of the 2015 regarding whether the ball is juiced, regarding the manufacturing standards and procedures of Rawlings and Major League Baseball. Now those questions are raised again. There seems to be enough smoke and testimonials to suspect the ball is different. Perhaps baseball needs to get together with Rawling and build a better ball.

After all, the World Series is not the time to be adding a new kind of variable — a new kind of ball.

We hoped you liked reading MLB Might Have Another New Ball and Controversy by Travis Sawchik!

Please support FanGraphs by becoming a member. We publish thousands of articles a year, host multiple podcasts, and have an ever growing database of baseball stats.

FanGraphs does not have a paywall. With your membership, we can continue to offer the content you've come to rely on and add to our unique baseball coverage.

Support FanGraphs

A Cleveland native, FanGraphs writer Travis Sawchik is the author of the New York Times bestselling book, Big Data Baseball. He also contributes to The Athletic Cleveland, and has written for the Pittsburgh Tribune-Review, among other outlets. Follow him on Twitter @Travis_Sawchik.

newest oldest most voted

Given that some pitchers have seen a decrease, and some an increase, in the amount of movement, in either dimension, I’d like to see some control data, e.g., comparison of regular season movement and postseason movement in 2016. Maybe changes like these are quite common in small sample sizes.

Also, assuming the ball is different, when exactly are people claiming it became different? Just for the WS this year? How did the pitchers take a blindfold test? Where did they get a ball that was not slicker, if that’s all that’s being used now?


This type of “research” is never going to be conclusive. It is just a headline and an interesting idea to think about.


Did you read the Verducci article referenced above? Some of your questions are answered there.


They make different balls for each postseason stage. You can see the Logos and insignia marked on the game balls for posterity