Poll: Do you think the new rules will speed up baseball?

Major League Baseball on Friday announced new rules designed to quicken the pace of its games, most notably a requirement that batters keep one foot in the box.

MLB also announced that clocks posted in each ballpark will count down to when the game resumes after each TV commercial break, with pitchers required to end warm-up throws with 30 seconds remaining and batters required to enter the box with no fewer than five seconds remaining.

In addition, managers wishing to call for an instant-replay challenge will now be able to do so with a signal from the dugout, rather than walking out to an umpire on the field.

Under the rules, players will be subject to warnings during spring training and in April, with fines thereafter. The league promised to donate to a players union charity "based on the level of adherence to the new rules."

Batters still can step out of the box under several conditions, including a swinging strike, wild pitch, passed ball, pick-off play or meeting at the mound.