One of the most consequential new rules — or enforcement of existing rules — is the pitch clock, with batters needing to be in the batter’s box and ready for the pitch. Pitchers must throw the ball at “14 seconds at all full-season levels, with additional time allotted ... for pitches with runners on base. At all levels, the hitter must be in the batter’s box and attentive to the pitcher with nine seconds left on the timer.”
These rules did not start right away; the first time they were implemented was on April 15. From some research by JJ Cooper of Baseball America, he found that “the average plate appearance took two minutes, five seconds [on April 15].