Kershaw and his evolving slider

Check out the evolution of the Dodgers' Clayton Kershaw from a fastball/curveball pitcher to a fastball/slider pitcher.

 2008

In 22 games (21 starts) in 2008, Kershaw was 5-5 with a 4.26 ERA and a 1.495 WHIP.

Kershaw in 2008 had a .264 batting average against

Kershaw threw 1891 pitches in 2008

Fastball - 68.0% (1286 pitches) - .291

Change Up - 4.5% (85) - .167

Curveball - 21.6% (408) - .153

Slider - 0.3% (6) .500

Cutter - 0.1% (1) .000

2009

In 31 games (30 starts) in 2009, Kershaw was 8-8 with a 2.79 ERA and a 1.228 WHIP.

Kershaw in 2009 had a .206 batting average against

He threw 3259 pitches in 2009

Fastball - 66.5% (2168 pitches) - .216

Change Up - 4.0% (130) - .355

Curveball – 16.8% (546) - .126

Slider – 6.9% (225) .143

Cutter - 0.6% (20) .000

2010

In 32 games (32 starts) in 2010, Kershaw was 13-10 with a 2.91 ERA and a 1.179 WHIP.

Kershaw in 2010 had a .214 batting average against

He threw 3390 pitches in 2010

Fastball – 70.5% (2390 pitches) - .243

Change Up – 1.3% (45) - .250

Curveball – 6.8% (229) - .290

Slider – 19.5% (662) .108

Cutter - 0.5% (16) .000

2011

In 32 games (32 starts) in 2011, Kershaw is 20-5 with a 2.27 ERA and a 0.987 WHIP.

Kershaw in 2011 has a .208 batting average against

He has thrown 3375 pitches in 2011

Fastball – 65.3% (2205 pitches) - .272

Change Up – 3.6% (122) - .059

Curveball – 5.2% (176) - .146

Slider – 24.1% (813) .117

Cutter – not thrown

The change in Kershaw has been both significant and successful. 

Clayton Kershaw's Platoon-Proof Slider

Is the Dodgers' Clayton Kershaw the best starting pitcher in baseball? If not, he's in the discussion. The 23-year-old left-hander has taken yet another step forward this season, increasing his strikeout rate, issuing fewer free passes and posting a 2.39 fielding independent ERA (FIP) that's bested by that of only Roy Halladay. Kershaw is enjoying his best season yet by shutting down right-handed hitters, and he's doing it with a wicked, platoon-proof slider.

Kershaw has long been death on fellow lefties, but his numbers against opposite-handed hitters have improved dramatically

Kershaw versus right-handed hitters:

2008: 1.71 strikeout-to-walk ratio, .269 batting average/.349 on-base percentage/.393 slugging percentage

2009: 1.41 K/BB ratio, .208/.325/.291

2010: 2.13 K/BB ratio, .218/.301/.298

2011: 4.52 K/BB ratio, .221/.271/.316

Basically, Kershaw is turning every righty hitter that he faces into the 2011 version of Alex Rios. Those righties are hitting his fastball pretty well, with a .314/.368/.432 line against the pitch that's well above the .273/.351/.431 average for righty batters versus lefty fastballs. But Kershaw's slider is another story.

Kershaw is using his slider against righ-handers 22 percent of the time this year, compared to 19 percent in 2010, five percent in 2009 and less than one percent in 2008. Righties just plain can't make contact with the pitch.

First, here's the average contact rate for right-handed hitters against left-handed sliders:

Now, here's the contact rate for righties against Kershaw's slider:

Right-handers have missed 41 percent of the time that they have pulled the trigger on a Kershaw slider, compared to the 28 percent average for righty hitters versus lefty sliders.

What makes Kershaw's slider so remarkable is that it's a killer pitch against batters swinging from both sides of the plate. Overall, sliders have one of the largest platoon splits of any pitch, with opposite-handed hitters faring much better against the offering. In 2011, left-handed pitchers have a .183/.212/.258 line against left-handed hitters when throwing a slider. Right-handed batters have a .207/.255/.326 slash against lefty sliders. But Kershaw's slider? Lefties are hitting .130/.167/.196, and righties have an even worse .087/.120/.173 line.

Most pitchers can't shut down opposite-handed batters with the slider, but Kershaw seems to be the exception to the rule. His increased use of that hard breaker and subsequent improvement against right-handers puts Kershaw in the same class as the Halladays, Lees and Lincecums of the world.

Pitcher of the Day: Kershaw Declaws Tigers

Los Angeles Dodgers lefty Clayton Kershaw continued his Cy Young-caliber 2011 campaign last night, tossing a complete-game shutout against the Detroit Tigers. Manager Jim Leyland sent out an all-right-handed lineup against Kershaw, and the 23-year-old responded by allowing two hits and one walk while tying a season high with 11 strikeouts.

Kershaw registered nine of his 11 K's with his slider. He located that wicked low-80s breaking ball at hitters' knees or handcuffed them on the inside corner:

 Kershaw's slider location against the Tigers on June 20, 2011

Detroit swung and missed at 10 of the 21 sliders that Kershaw broke off.

While he was once known for a knee-buckling curveball that Dodgers announcer Vin Scully dubbed "Public Enemy Number One," Kershaw has essentially scrapped his curve while going to his slider more and more frequently. Kershaw has thrown his slider a little more than 23 percent of the time this season, compared to about five percent for the curve.

Opponents are hitting .106/.140/.163 against Kershaw's slider this season. Batters have swung and missed at the pitch nearly 42 percent of the time, the sixth-highest rate among MLB starting pitchers.

The slider is a pitch that tends to have a large platoon split. But, as Kershaw showed against the Tigers, he isn't afraid to use the slider against righties. Kershaw has used his slider at a nearly equal rate against lefties and righties, and right-hander hitters are actually faring worse against the offering (.088/.116/.132 in 2011). Maybe it's time to start calling Kershaw's slider "Public Enemy Number One."