The Shift Restriction
Four infielders, all on the dirt, two on each side of second base when the pitch is released.
What it actually is. Since 2023 all four infielders must have both feet on the infield dirt and be positioned two on each side of second base at the moment the pitch is released. They cannot switch sides during an at bat. A violation lets the offense choose an automatic ball or the result of the play.
What somebody who knows the game gets out of it. The rule was aimed at raising batting average on balls in play for left handed pull hitters and it did, though by less than expected. The more interesting result is what clubs did next: they kept shifting inside the rule by moving outfielders, so the four man outfield and heavily shaded outfield alignments increased. Positioning value did not disappear, it moved to a part of the field the rule does not govern, which is what usually happens when a rule restricts an optimization rather than removing the incentive for it.
The numbers worth knowing. League batting average on ground balls by left handed hitters rose several points. Shifts had been used on roughly a third of all plate appearances before the restriction.
What people get wrong about it. The restriction is on positioning at the moment of the pitch, not afterwards. Fielders may move as soon as the ball is released, which is why you still see second basemen finishing plays in shallow right field.
At Little League and travel ball. There is no shift restriction at youth level and shifting is rare anyway, because the ball is not pulled with the consistency the shift depends on. What does apply is basic positioning by hitter, and Read the Play on this site covers the alignments that actually pay off at youth level.
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