(Redirected from Chase Utley rule)
Sliding is the action by which a baserunner finishes his run towards a base by taking a prone position, either feet-first or head-first. The main purpose of a slide is to slow down and not overrun a base, or to avoid a possible tag. The invention of the slide is often attributed to Bob Addy, back in 1866.
There is a misconception that sliding will make a runner reach the target base faster; that is not the case, but a batter-runner will occasionally slide into first base in an attempt to beat out a close play. Unless he is attempting to avoid a tag because the fielder has been pulled off his base, this move will actually slow him down, in comparison with running through the base as is allowed at first base.
Sliding is inherently dangerous, although proper technique can greatly reduce these risks. Risks to the runner includes jamming or twisting an ankle if going feet-first, or hurting a hand or finger when sliding head-first. More serious injuries can also occur while sliding, but these are rare. Sliding is also potentially dangerous for any nearby fielders, as a runner going feet first risks lacerating the fielder with his spikes, or barreling him to the ground, causing a number of possible injuries. Because of this, the rules related to sliding have been clarified over the years, with the most important modification coming before the 2016 season, after an incident in the preceding year's postseason involving baserunner Chase Utley injuring SS Ruben Tejada. This new rule, which has been dubbed informally the "Chase Utley Rule", aims to prevent baserunners from going out of their way to run into a fielder, or make other dangerous moves such as sliding after the base or sliding shoulder-first into a fielder. These outlawed tactics are often used in trying to break-up a potential double play. If such actions occur, the umpires are instructed to call the runner out, and to treat the double play as if it had been successfully completed.
- Paul Hagen: "Slip slidin' away: New rules music to all ears? 'Neighborhood play' at second base also to be subject to review", mlb,com, February 25, 2016. 
- Thomas Harrigan: "Remembering some of baseball's best slides", mlb.com, April 25, 2021. 
- Jake Mintz: "These are the five most exciting types of slides", "Cut4", mlb.com, May 16, 2018.