MLB rule changes mean big stat moves—but for which players?

This year will bring some of the biggest rule changes ever to Major League Baseball—but what does that mean for baseball’s all-important player stats?

Chaos is expected, especially early in the year as players, managers and umpires try to adjust. Meanwhile, sportsbooks, daily fantasy sites and their customers are trying to figure out the effect the rules will have across the game.

The expectation is that the changes could bring significant moves in some stats, but may affect individual players very differently. And some impacts will be immediate but others may take months or years to fully take effect.

For those in daily fantasy or fantasy baseball, who exactly will be affected and how long it’ll take for these changes to occur are critical. With little precedent or real data on which to base their analysis, many will be closely watching spring training games and the first games of the regular season—and odds and lines could shift substantially as a “new normal” gets established. 

Uneven effects

A number of the changes are designed to increase scoring, speed up the game and increase entertainment value of the game. For batters this is generally a good thing. But the effects will be uneven.

The new shift rule requires all four infielders to stand on the infield dirt, with two players on each side of second base—thus preventing shifts from cutting batting averages. Batting averages dropped to .243 in 2022, the lowest since way back in 1968 and the drop in singles was particularly bad.

The changes should help certain hitters the most—namely, pull hitters and those who hit hard ground balls. That’s because pull hitters had the shift put on them the most, and those who hit hard ground balls would otherwise have had hits more often without the shift.

Corey Seager hit an MLB-high 71 hard-hit ground balls into the shift in 2022. But he's not the only one who could benefit from the new rules.

As shifts have increased over the past several years, the overall batting average for hard-hit ground balls has plummeted from .313 in 2017 to .273 last year. This especially affected players who hit the most hard-hit ground balls, such as Corey Seager and Matt Olson. Seager hit only .176 on hard hit ground balls last year, compared to .385 in 2016 when the shift was much less common. He hit a MLB-high 71 hard-hit ground balls into the shift last year.

While Seager may be an especially bad case as a left handed dead-pull hitter, he won’t be the only one to benefit from the new rules. Looking deeper at the data, there were 23 players with a higher average exit velocity in 2022, according to Baseball Savant. There were also 55 players who had a higher “hard hit” rate and 39 players who had a higher barrels-per-plate-appearance rate. So other players could benefit as well—even if they aren’t dead pull hitters.

More generally, in the minors last year after the shift rule was implemented, left handed batters, who are often pull hitters and against whom defenses shifted the most, saw BABIP rise 8 points, compared to 3 points in Triple A, which didn’t have the new rule. Some believe certain pull-happy hitters could see batting averages rise as much as 40 points.

Signal from the noise

Still, the average hitter’s batting average may not rise much. Or rather, it may not rise much due to the shift. Some believe the shift rule may not have that big of an impact on batting averages. For example, minor league data from 2021, when the shift rule was implemented, shows that batting averages for balls in play (BABIP) actually didn’t increase substantially.

In Double-A with the shift rule, BABIP for 2021 was .308, up from .305 in 2019 but down from .309 in 2018. In 2022, in Double-A with shift restrictions again, BABIP went up to .311 from .308. In High-A, which added shift restrictions last year, BABIP dropped by seven points, and in Low-A BABIP dropped 6 points. In Triple-A, which had no shift restrictions in 2022, BABIP went up to .311 from .310. The upshot: it’s hard to extrapolate from limited minor league data.

Hard-throwing pitchers who used to take long breaks between pitches may be more tired due to the pitch clock. Still, the pitch clock may also negatively affect some hitters—who have to adjust their batting gloves' velcro after each pitch.

Meanwhile there are several other rule changes that could affect batting averages, runs scored and other offensive categories. The pitch clock, the pitcher’s disengagement rule and the larger bases could all have some impact on offensive categories.

With the pitch clock, it’s possible that hard-throwing pitchers who used to take long breaks between pitches may be more tired now with limited time to rest between pitches, which could lower their performance. But again, this may affect some pitchers more than others—and some may adjust easier than others. Brent Suter was the fastest pitcher last year at 12.6 seconds between pitches with the bases empty, while Jonathan Loaisiga was the slowest at 25.8 seconds. But which of the slowest pitchers threw the hardest? And will their ERA and WHIP rise with the new rules? 

At the same time, the pitch clock may also negatively affect some hitters—who have to adjust their batting gloves' velcro after each pitch.

Player responses

There is much that’s still unknown. First, even with the new shift rule, outfielders are still allowed to move around, meaning a team can put a left fielder in right field for left-handed pull hitters. That would leave defenses open to triples or inside-the-park home runs on balls hit to left field—but some may think it’s worth the risk in certain situations. If you believe Corey Seager really just can’t hit a ball to left field, go for it. So it’s unclear if outfielders shifting could mitigate some of the intended increase in batting averages.

The bigger issue is how batters and teams will respond to the shift rule. Will they try to hit more ground balls or line drives or try to focus less on launch angle—which has been a major emphasis in recent years? There is reason to believe that at least some batters will go back to the pre-launch angle hitting approach, since they will no longer be penalized for hard-hit ground balls. But it’s unclear how long that would take to filter through the league. It could take until later this summer or next year for hitters to change their swings.

Get ready to run

MLB made a number of changes designed to increase steals, which are way down in recent years. One rule limits pitcher “disengagements”—stepping off the rubber or making a pick-off attempt. Another is the pitch clock. Then there are the larger bases. The disengagement rule will make it more difficult for pitchers to hold runners on base and extremely hard after two disengagements—since the third disengagement must result in a pitcher throwing the runner out or it is a balk.

In the minor leagues in 2021 and 2022, when the rules were implemented, steal attempts and successful steals jumped substantially. But how will that play in the majors and will teams that have adhered to the Moneyball idea that steals are a waste now change philosophies?  

Meanwhile, the pitch clock could give runners the ability to better time their steal if the pitch clock is running down close to zero. In certain situations, such as runners on first and third, it could get wacky as runners try to get the pitcher to throw over and trigger the 3 disengagements, resulting in a balk.

Ultimately, everyone following baseball will be figuring this out in real-time. For baseball purists who hate change it could take some getting used to. (Can we get rid of the ghost runner?) And it could be confusing if you’re trying to tease out data or analysis from the various changes in order to play daily fantasy or even create odds or lines. But one thing’s for sure—it will be entertaining.

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