Clayton Kershaw, Jose Fernandez and the evolution of great sliders

Last Saturday, Jose Fernandez struck out 14 New York Mets batters without issuing a walk. Twelve of those strikeouts were with his slider, the most by a pitcher in a single game since Francisco Liriano had 12 in 2012.

Only two other pitchers have had at least nine strikeouts with their sliders in a start this season. And one of them is three-time Cy Young winner, Clayton Kershaw.

Kershaw and Fernandez have stuck out a combined 113 batters with their sliders this season. They both rank in the top four in baseball in terms of strikeouts via the slider this season.

But believe it or not, sliders weren’t always the go-to pitches for these players.

In 2011, Kershaw nabbed a league-high 138 strikeouts via his slider, 61 more than he had in his previous two seasons combined. He won his first Cy Young in 2011. Since then Kershaw has steadily increased his slider usage to more than 33 percent this season, a career high.

Fernandez has more than doubled his slider usage since winning National League Rookie of the Year in 2013. The Miami Marlins ace threw 312 sliders in his rookie campaign. He has thrown 351 sliders through 12 starts in 2016.

Kershaw: Master of location

Why is Kershaw’s slider so effective? Location, location, location.

Kershaw has gotten batters to chase his slider on 48 percent of pitches outside the strike zone, the second-highest rate of his career. The Los Angeles Dodgers lefty is also getting called strikes on 30 percent of sliders taken, his highest rate since 2010.

This season, 35 percent of Kershaw’s pitches to right-handed batters have been sliders, up from 27 percent last year. He is holding opposing batters to an MLB-best .100 batting average on sliders thrown on the inner half of the plate (minimum of 125 such pitches), a mark he hasn’t hit since 2011. He's locating the pitch inside more often to right-handers as well, as the images below show.

Fernandez: Master of deception

Fernandez used his slider on 12 percent of pitches in his rookie season, getting batters to miss on 40 percent of their swings against the pitch. This season his slider usage is up to 29 percent, and his miss rate with the pitch is an MLB-best 53 percent.

Fernandez’s high miss rate could be attributed to the unsuspecting movement of the pitch. On average, his slider breaks more than seven inches horizontally in the final 40 feet of its path to home plate.

Translation: A Fernandez slider could look like any pitch from 40 feet away before darting left-to-right from the batter’s point of view.