Opening Day Is When Baseball's New Rule Changes Get Real

As Major League Baseball starts its season, three big rule changes are shaking up the American pastime.

Peter Butler
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a baseball sits on a pitching mound while a pitch clock with 20 seconds on it is shown in the background

The most obvious change at professional baseball games is the new pitch clock.

Mike Carlson/Getty Images

Professional baseball starts its 2023 season today with a full slate of games all over the country. While Major League Baseball's Opening Day is a longstanding tradition, the game looks a bit different this year. New rules taking effect this season make big changes to pitching, hitting and baserunning.

The MLB is making these rules changes for 2023 in an effort to shorten game times, increase offense and improve safety. Learn all about the new MLB rule changes this year and how they have been implemented.

What are the new rules in Major League Baseball for 2023?

In an effort to speed up games, encourage base stealing and prevent stifling of power hitters, Major League Baseball is implementing three main rule changes for the 2023 season:

  • Introducing a new pitch timer
  • Increasing the size of the bases
  • Eliminating the "defensive shift"

All three rules were tested in MLB's minor league systems in 2022.

How does the new MLB pitch clock work?

Starting in 2023, pitchers now have a time limit to deliver their pitches: 20 seconds with runners on base or 15 seconds when the bases are empty. If a pitcher does not start to throw before the timer ends, a ball will be called.

There's a 30-second timer in between batters, and hitters must enter the batter's box by the 8-second mark or be charged with an automatic strike. 

The pitch timer is designed to speed up the pace of baseball games, which averaged more than 3 hours in 2022. During the rule's testing in the 2022 minor-league seasons, games were 25 minutes shorter on average than before the rule. 

This year's spring training showed a similar decrease in the average game length. MLB preseason games this year were 26 minutes shorter on average than last year.

The MLB pitch clock also brings a new pickoff rule with it. Pitchers are limited to only two "disengagements from the mound" per batter. That means a pitcher can only try to pick off the runner or step off the rubber twice. 

A pitcher may disengage a third time, but unless an out is recorded or the runner advances a base, the disengagement will result in a balk, meaning all runners advance one base.

The new limit on the number of allowed pickoff attempts is likely to encourage more base stealing. In 2023 spring training, there were 40% more stolen base attempts compared to 2022.

How is MLB changing the size of bases in baseball games?

The league is expanding the size of bases in 2023, beefing them up from 15 inches square to 18 inches square. Home plate remains the same size.

The main reason for bigger bases is safety. The larger area gives fielders and runners more room to share the base without crushing each other's feet. 

However, increasing the bases by 3 inches on each side means that the bases are 4 1/2 inches closer to each other. The distance from home plate to first and third base to home is now 3 inches shorter. Those few inches could be significant for base stealers or for "bang-bang" plays where the ball and the runner reach the base at nearly the same time.

Why is the MLB banning the defensive shift?

In recent years, a baseball tactic called the defensive shift has been increasingly adopted around Major League Baseball. A team will move one or more infielders to the opposite side of the diamond to defend better against "pull hitters" -- batters who frequently hit to right field if left-handed or left field if right-handed. 

Because the first baseman is required to cover first base, defensive shifts have been used in the past occasionally against star left-handed hitters, but the practice became widespread in the 2010s when managers realized that many players often hit in the same direction.

A new MLB rule for 2023 ends the most common defensive shift of moving a shortstop over to second base or second baseman over to short, with one of them in shallow outfield. Starting this season, teams must have at least four infielders at all times, with two infielders on each side of second base. Those four infielders must also be standing with both feet on the infield dirt. Teams can still bring in an extra outfielder to have five infielders.

According to MLB, the reason for the defensive-shift rule change is to "improve the likelihood of balls in play leading to more traditional outcomes and to showcase the athleticism of rangy defenders up the middle." The league notes that batting percentage on balls in play in 2022 was .290, seven points lower than a decade earlier.

What about the ghost runner in extra innings and other rules?

The three rules above are the big changes, but MLB is also expanding the "ghost runner" in extra innings to playoff games and making the rule permanent. Beginning in the 10th inning, each team starts with a runner on second base.

MLB is tightening the restrictions on position players pitching, too. In order for a non-pitcher to take the mound, one of three criteria must be met: the game is in extra innings; the player is on a team losing by eight runs or more; or the player is on a team winning by 10 runs or more in the ninth inning.