infield shift

Etymology
From infield and shift.

Originally called the Williams shift or Boudreau shift, respectively named for Ted Williams and Lou Boudreau, and first used during the 1946 World Series by St. Louis Cardinals manager Eddie Dyer as a defensive gimmick. In the late 1990s, the strategy was revived, using the more generic infield shift, which has been used exclusively since then.

Noun

 * 1)  A defensive alignment in which the third baseman, shortstop and second baseman positionally shift to their left when a left-handed batter is in the batter's box. Used primarily when the batter is an extreme pull hitter.