Clayton Kershaw Has Big Head Start on MLB's Best-Ever Left-Handed Aces

Zachary D. Rymer@zachrymerMLB Lead WriterJuly 4, 2014

The thing about Clayton Kershaw's greatness is that it's both easy to talk about and actually pretty hard to exaggerate.

For example, we can say the Los Angeles Dodgers ace lefty is hands down MLB's best pitcher. There's plenty to back that up, including how Kershaw's 2.19 ERA since 2011 is easily the best among pitchers with at least 100 starts.

For another example, we can say the no-hitter Kershaw pitched against the Colorado Rockies—who face him again Friday night—on June 18 is an all-time great performance. After all, it's the only no-hit, no-walk game ever to feature 15 strikeouts.

Here's another one: Though he's still only 26 years old, Kershaw has a very real chance of becoming the greatest left-handed ace baseball has ever known.

Between the three statements I just threw out there, this is probably the one that comes off as being dangerously close to an exaggeration. Or maybe even a full-blown exaggeration.

But if anything, it's the lesser exaggeration of the three. Of all the great southpaws baseball has ever known, none of them was as good at such a young age as Kershaw is now.

In simpler times, we would have turned to wins for a primary measuring stick. But in these less simple times, we'll turn to wins above replacement (WAR) to at least get us started.

According to's WAR, Lefty Grove and Randy Johnson are the only lefties ever to top 100 career WAR. Only eight others have so much as topped 60 career WAR.

And as we see here, only one of the plus-60 WAR lefties had compiled more WAR through his age-26 season than Kershaw has:

Kershaw vs. All-Time Lefties: WAR Through Age-26
Hal Newhouser1939-19471894.042.9
Clayton Kershaw2008-20141259.135.2
Steve Carlton1965-19711265.120.9
Andy Pettitte1995-1998852.219.2
Tommy John1963-19691109.017.0
Tom Glavine1987-19921117.215.9
Warren Spahn1942-1947431.011.3
Eddie Plank1901-1902560.211.1
Lefty Grove1925-1926454.09.5
Carl Hubbell1928-1929391.26.3
Randy Johnson1988-1989186.20.1

You can tell by looking at the innings that some of the greatest southpaws ever were still just getting started by the time they hit 26, including the Big Unit, Carl Hubbell, Grove and Eddie Plank.

Also standing out is how the only all-time lefty who was as accomplished as Kershaw by 26 was Hal Newhouser. That's true even if we expand the field to include all lefties ever through age 26. Do that, and Newhouser and Kershaw are still at the top.

But was Newhouser able to compile more WAR than Kershaw has because he was a better pitcher or simply because he pitched more innings?

We can turn to another statistic that leans definitively toward the latter explanation.

This statistic would be ERA+, which takes ERAs and essentially puts them on a level playing field. It does that by adjusting for park factors and league standards and putting everything on a scale where 100 is average. Anything over 100 is better than average.

The career ERA+ leaderboard (minimum 2,000 innings) for lefties is even pickier than the WAR leaderboard. Grove owns the best career ERA+ at 148, and only seven others are over 130.

If we look at where these eight guys were through their age-26 seasons compared to where Kershaw is now, what we see is this:

Kershaw vs. All-Time Lefties: ERA+ Through Age-26
Clayton Kershaw2008-20141259.1148
Johan Santana2000-2005856.0140
Hal Newhouser1939-19471894.0139
Rube Waddell1897-19031153.1136
Whitey Ford1950-1955783.1134
Carl Hubbell1928-1929391.2127
Lefty Grove1925-1926454.0126
Sandy Koufax1955-19621131.2110
Randy Johnson1988-1990186.297

Here's where we find Kershaw on top, and there are two things worth noting:

  1. It's not really close.
  2. Once again, things don't change if you expand the field.

Only 66 southpaws have ever logged as many as 1,000 innings by their age-26 seasons. Of the bunch, Kershaw's 148 ERA+ is the highest by nine ticks over the next best ERA+.

Which belongs to Newhouser at 139. He may have racked up more innings and more WAR through his age-26 season than Kershaw has, but his innings did the trick more so than his pitching.

And no, ERA+ is not the only stat that says so.

ERA+ has one notable flaw: It's based on ERA. That's a flaw because ERA is flawed, as it can be influenced by many things besides a pitcher's talent.

That's why we have stats like fielding independent pitching (FIP), which is a metric that determines what a pitcher's ERA should be by focusing mainly on strikeouts, walks and home runs.

And just as we have ERA+ to put ERAs from different eras on a level playing field, we have FIP- to do the job for FIP. It works basically the same way ERA+ does, except the other way around. Whereas a higher ERA+ is better, a lower FIP- is better (hence the minus).

As for how FIP- rates Kershaw's career, here's a hint: It likes what it sees.

According to FanGraphs, Kershaw's career FIP- of 73 is fifth-best among all pitchers with at least 1,000 innings through their age-26 seasons and the best among lefty pitchers.

That means Kershaw's high standing in the eyes of ERA+ is not a mirage. He legitimately has pitched better than any other young lefty pitcher baseball has ever seen.

That includes the one guy he's most often compared to: Sandy Koufax.

There's no need to tell Kershaw about how he and Koufax have been joined at the hip. Not surprisingly, he feels the honor is all his.

"If you're going to get compared to somebody, that's the guy," Kershaw said of the former Dodgers star to last month. "It's the biggest honor you can get. But I also take that with a grain of salt. In his prime, he was the best ever. I have to get a lot better to prove that right."

Kershaw isn't wrong about Koufax's prime. Beginning with his age-26 season in 1962 and ending in his age-30 season in 1966, Koufax racked up a 1.95 ERA, 40.9 WAR, a 167 ERA+ and a 66 FIP-. That's undeniably one of the great pitching runs in baseball history.

To this end, Kershaw's right about another thing: He'll have to get even better if he wants to put together a prime to match Koufax's.

Here's the thing, though: The process of doing so has already begun.

Where Koufax was able to make the leap from good pitcher to great pitcher in his age-26 season, Kershaw is using his own age-26 season to make the leap from great pitcher to...well, something else entirely.

Kershaw has never been better at striking guys out, limiting walks and getting ground balls, and it's reflected in his FIP and FIP-, via FanGraphs:

Clayton Kershaw's Progressing Dominance, 2008-2014

Kershaw was awfully good between 2011 and 2013. When he hurt his back earlier this year, you had to wonder if maybe he would become human again.

Instead, the exact opposite has happened. As FanGraphs' Tony Blengino put it:

Whatever worries any of us had about the big lefty after his DL stint due to an inflamed back muscle earlier this season have been allayed. They simply don't make them any better than Clayton Kershaw, circa 2014.

The mind boggles to comprehend it, but it's happening. A pitcher who can already lay claim to being the best young lefty ever is just now starting to show how great he can be.

Don't be shocked if the next few years of Kershaw's career rival or surpass what Koufax did between 1962 and 1966. Be even less shocked if we have every reason to celebrate him as the best southpaw in baseball history when his career comes to a close.

These are not exaggerations. This is simply the path he's on.


Note: Stats courtesy of unless otherwise noted/linked.

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