Says the Washington Post:
The defensive shift isn’t new.
The alignment first surfaced in the 1920s as a way to neutralize left-handed Phillies slugger Cy Williams and became famous in the 1940s when Cleveland Indians manager Lou Boudreau put six fielders on the right side of second base against Ted Williams of the Boston Red Sox, which became known as the “Ted Williams shift.”
Recently, however, its use has exploded:
In 2018, there were 40,730 plate appearances featuring a defensive shift compared to 33,218 in 2017 and just 14,972 five years ago.
Some, such as Kansas City Royals Manager Ned Yost, have voiced skepticism of its benefits, even calling for it to be banned altogether from the sport, yet that didn’t stop his club from using it 1,706 times last season, the fifth-most in baseball.