We create "5 o'clock hitters" guys that are great hitters in batting practice but struggle to adjust in the game. In practice coaches tell the hitter to "be on time" and congratulate them when they execute a "timed up swing." However, the way to be a great hitter is having the ability to be early or late and still make solid contact. In practice we need to mix pitches and speeds so the hitter can learn how to adjust when he is early or late. The reality is in the game you are not on time very often but in a normal batting practice you are. Your players will initially be very uncomfortable with you mixing pitches and speeds but continue to remind them that we are not trying to be the best cage hitter, we are trying to get our swings ready for the game.
