How Rule Changes Will Impact MLB Play in 2023 and Beyond

With the 2023 Major League Baseball season set to begin on March 30th, the game will be played more efficiently than it has in decades. The impact of the changes have been studied based on minor league play last year. The changes have reduced the length of spring training games by about 30 minutes. Let’s think about how the game might be played differently, based on recent trends and the impact of the rule changes.

1. A majority of teams will be using a six-man rotation by 2025. Teams already rely on 8-11 starting pitchers over the course of a season. In 2022, the Mariners, Twins and Mets all used a six-man rotation at times. This year, the Angels, Athletics, Mets and others have said they’ll rotate through six starting pitchers, at least for stretches. Tampa Bay regularly uses an "opener" and other teams have followed the trend, on occasion, in recent years. Pitchers get injured so often that it makes sense to expand the rotation in hopes of limiting injuries and reducing a pitcher's total innings per season.

2. Stolen bases will increase every year for the next five years. In the minors, stolen base success rates increased from 72-78 percent with the new rules in place. With limited pickoff attempts per at-bat, stolen base attempts jumped by 26 percent. If the trend continues this year in MLB and runners become close to 80 percent successful in their steal attempts, even analytics-focused teams will give more runners the green light.

As the 2018 and 2019 seasons recede into the past, and the recently juiced ball is gone, home runs become harder to hit, which increases the value of the stolen base and general "small ball" strategy. The new rule limiting pitcher "disengagement" to two times per at-bat gives the smart and speedy runner a distinct advantage. Baseball's blazing young prospects will advance through the minors with these rules in place and will become better at the cat-and-mouse game of taking off and swiping that (now slightly bigger) base.

3. Elite athleticism will become absolutely critical for middle-infielders again. Gone are the days of power-hitting but athletically-limited second baseman. Without the shift, the middle infielders will be forced to make more diving stops, sprinting catches and glovework that generally involves agility and physical contortions.

4. Doubles and triples will increase. With homers and run-scoring on the decline, the emphasis on speed is on the rise. More hitters will attempt to stretch those gap singles into doubles and those line-drives into the gaps and down the right field line into triples. We'll see 15+ triples for some hitters again like we did with Juan Samuel, Willie McGee, Jose Reyes and Jimmy Rollins.

5. Walks may increase this year and then decrease over the next few years. When the at-bat speeds up, the average pitcher has slightly less rest time between pitches, which means the pitcher would be expected to show more fatigue later in each at-bat. By pitch five or six of an at-bat, especially in a particularly long inning, the pitcher would theoretically lose some command. This would lead to more walks and more extra-base hits in 2023. But, I’d expect pitchers and pitching coaches might adjust to this by further emphasizing first-pitch strikes and pitching to contact, rather than emphasizing strikeouts (and potentially walks). With a reduced threat of the home run, the temptation to attack the strike zone and reduce the length of each at-bat goes up.