The strike zone currently is defined as:
The STRIKE ZONE is that area over home plate the upper limit of which is a horizontal line at the midpoint between the top of the shoulders and the top of the uniform pants, and the lower level is a line at the hollow beneath the kneecap. The Strike Zone shall be determined from the batter’s stance as the batter is prepared to swing at a pitched ball.And it previously looked like:
1887: Batsman's knee - shoulders;
1907: Batsman's knee - shoulders (Adopted by both National and American Leagues)
1950: Top of the knee when batter assumes a natural stance - armpits;
*NOTE: 1957 was the Adoption of Rule 2.00 [Strike] referencing Rule 2.00 [Strike Zone]*
1963: Top of knees when batter assumes a natural stance - top of shoulders;
1969: Top of knees when batter assumes a natural stance - armpits;
1988: Top of knees when prepared to swing - midpoint between top of shoulders and top of pants;
1996: Hollow of the knees when prepared to swing at pitch - midpoint b/w top of shoulders/pants.
*NOTE: 2014 renumbered Rule 2.00 [Strike Zone] to Definition of Terms [Strike Zone]*
Key: Green = Strike Zone Expansion; Red = Strike Zone Shrinkage; Yellow = Stayed the same.
The 2016 strike zone proposal would favor the offense by raising the lower bound of the strike zone to the top of the knees while keeping the upper limit at the midpoint.
during the 2014 Arizona Fall League, when the League tested several pace of game proposals, including the since-adopted batter's box rule (except without the penalty of a dead ball strike) and inning/pitching change intermission clocks.
Needless to say, elimination of the four thrown balls requirement would eliminate: increased pitch counts; the potential for a wild pitch or passed ball, a pitcher or catcher's balk, a batter swinging at a poorly placed intentional ball, a stolen base; and the 30-seconds to one minute it takes to intentionally walk a batter.
The two proposals now stand for a players' union vote and, if they pass in a timely manner, could realistically be implemented in 2017. If they don't pass in time for Spring Training or the season, there likely would be no change made for the beginning of the 2017 season.