Comparing Clayton Kershaw's Early Prime to Sandy Koufax

Zachary D. Rymer@zachrymerMLB Lead WriterJuly 18, 2013

Start up a conversation about the best pitcher in baseball, and there will be some debate.

If that's not what you're looking for, you're better off starting up a conversation about the best left-handed pitcher. Rather than a debate, what you'll get is a geek-out session over Clayton Kershaw.

The Los Angeles Dodgers southpaw is in the middle of his finest season, as he entered the break with a 1.98 ERA over 145.1 innings. Barring an injury, the 25-year-old is on his way to a fourth straight season with an ERA under 3.00 and more than 200 innings pitched.

The last southpaw to post seasons like that four years in a row before crossing over to the other side of 30?

Per, just some guy named Sandy Koufax. He did it between 1963 and 1966 when he authored arguably (or maybe not) the greatest stretch of pitching in baseball history.

Just how good was that stretch? Well, I'll put it this way: it's probably the only thing in the universe that can make the run Kershaw is on now look petty by comparison.

I know this because I went ahead and made said comparison. This was after I ignored all my more level-headed instincts, of course, as they were shouting that nothing should ever be compared to Koufax's stretch between '63 and '66. I did it anyway in the interest of fun and what-the-heckery.

If you're in the mood for some fun and what-the-heckery, just keep reading.

The first order of business is to get a general idea of how good Kershaw is now compared to how good Koufax was then. We're going to do that by focusing on some simple statistics, which I have arranged nicely in the following table:

 Koufax 1963-1966 150 1192.270 1.86 0.91 172
 Kershaw 2010-2013 118 810.263 2.45 1.03 153
*Note: Links go to

The only thing that should need to be explained here is "GmSca." That stands for Average Game Score, which is just what it sounds like if you know what game score is.

If you don't, it's a stat that Bill James created a while back that evaluates how good a given start was. You start with 50 points and add and subtract points based on innings pitched and various outcomes. For some perspective, a game score of 60 in a given start is pretty darn good.

Now that we've gotten that out of the way, we can go ahead and get this out of the way:


Yes, yes he was. He logged innings and virtually all his starts were gems, hence the reason his ERA, WHIP and ERA+ sparkle the way they do.

Of all the stats in the above table, ERA+ is obviously the key one as far as our comparison to Kershaw is concerned. By adjusting for leagues and ballparks, ERA+ makes it possible to compare pitchers from different eras. In this case, what we get is a message confirming that, yes, Koufax really was that good.

It's not that Kershaw's numbers themselves are lacking. They're anything but, actually. All you really need to know is that there's not a starting pitcher in baseball who has a better ERA+ than him since the start of 2010.

Kershaw just isn't that much better than his contemporaries as Koufax was to his, as his ERA+ between 1963 and 1966 exceeded the next best guy's by 20. He was practically a god of his time.

That has a lot to do with the fact that Koufax was so much better at striking guys out than everyone else.

We're about to compare Koufax and Kershaw as strikeout pitchers, but not just side-by-side. It's important to take the environments in which they pitched/are pitching into account so we can consider how much better they were/are at striking guys out as compared to other pitchers around the league.

This is where a tip of the hat is owed to FanGraphs for keeping track of league-wide strikeout totals for starting pitchers. Without their number-crunching, it would have been a lot harder to draw up numbers for starting pitchers between 1963 and 1966 and 2010 to the present day.

Right then, here we go with another table:

 Koufax 1963-1966 26.3 15.4 +10.9
 Kershaw 2010-2013 25.7 18.1 +7.6
PlayerSpanK%League K%Difference

*Note: Links go to FanGraphs.

For the record, these are strikeouts recorded as a starter only, so I did remove the four strikeouts Koufax racked up as a reliever in 1964 and 1965. In the words of Morgan Freeman from Batman Begins, I just want you to know how hard I worked.

At any rate, what we have here is another case of our socks being blown off by the greatness of Sandy Koufax. He struck out batters at a higher rate between 1963 and 1966 than Kershaw is now, and he did it in a relatively low-strikeout environment. 

And before you chalk that up to the pitchers, remember that hitters were different in those days too. They cared more about not striking out than today's hitters, who generally (and rightfully) don't view strikeouts as an attack on their pride.

It wasn't just the strikeouts that made Koufax great, however. He was also very good at not issuing free passes.

We're going to do the same thing here that we just did with strikeouts, except with walks. Here's the obligatory table:

 Koufax 1963-19665.67.5-1.9
 Kershaw 2010-20137.27.6-0.4
PlayerSpanBB%League BB%Difference

In terms of walks, the environment Koufax was pitching in between 1963 and 1966 is surprisingly similar to the environment Kershaw is pitching in now. It's almost like, I don't know, pitchers didn't like issuing them and hitters didn't mind taking them in those days. Weird (he said with his tongue in his cheek).

But once again, it's Koufax who gets the top marks. Kershaw is one of the better pitchers in the league at not walking batters, which is something he certainly deserves credit for given how wild he was earlier in his career. He just so happens to be standing (figuratively) next to a guy who barely walked anyone when he was in the thick of his prime.

The impressive strikeout and walk numbers speak to the very basic thing that Koufax did better than any other pitcher: get hitters out.

If you're getting tired of the Koufax worshiping, here's a spoiler about this next comparison: in it, Kershaw actually has a fighting chance.

What we're going to do is consider how good Koufax and Kershaw are/were at overwhelming hitters. Opponent OPS will do as a tell-tale stat, as it's available for both pitchers and tells us all we need to know: how good they were/are at keeping hitters off the bases and from hitting for power.

Here's a table:

 Koufax 1963-1966.518.686-.168
 Kershaw 2010-2013.573.723-.150
PlayerSpanOpponent OPSLeague OPSDifference

*Note: Links go to

Koufax racked up an otherwordly opponent OPS between 1963 and 1966, and he did so while pitching in an offensive environment inferior to the one Kershaw is pitching in now.

Hence the relative closeness between the two in the "Difference" column. Koufax was still more dominant for his day and age than Kershaw is for his day and age, but there's not such a huge disparity between the two. Kershaw is almost as dominating now as Koufax was then.

As far as compliments I can pay Kershaw, that's not a bad one. Heck, if I were to walk up to any other pitcher and say, "Hey, you've been almost as dominating these last couple years as Sandy Koufax was between 1963 and 1966," that pitcher would probably wet himself and then retire on the spot so as to go out on top.

Believe it or not, though, there's actually a better compliment I can pay Kershaw.

The sheer ridiculousness of Koufax's numbers between 1963 and 1966 is a big part of what makes this comparison so darn unfair in the first place.

But another hitch in this comparison is the fact that we're talking about a stretch ranging from Kershaw's age-22 season to the middle of his age-25 season. Koufax began his dominant stretch in his age-27 season and capped it off in his age-30 season. He'd had more time to mature as a pitcher than Kershaw has so far.

Indeed, Kershaw is actually a better pitcher now than Koufax was at the same stage of his career. Between his own age-22 and age-25 seasons (1958-1961), he only compiled a 3.93 ERA and a 106 ERA+. He was good, but he wasn't yet the great Sandy Koufax.

In light of that, here's the scary part about Clayton Kershaw: he's really good, but there's a chance he might not yet be the great Clayton Kershaw.

This final table suggests the transformation may have already begun:

 Koufax 1963-1966 70 1.86 0.91 17226.45.6.518
 Kershaw 2013 67 1.98 0.91 18124.86.3.510

You knew coming into this piece that Kershaw was in the middle of a terrific season. Now we all have a new word to describe it: Koufaxian.

Not bad for a guy who's only 25, an age at which the majority of pitchers are only just getting started. For Kershaw, the age of 25 is looking like more of a next step. And if it is, perhaps this Koufaxian season will prove to be the start of a Koufaxian run.

If it comes to that, the next comparison I tackle between the two won't be in the interest of fun and what-the-heckery. It will be in the interest of dead seriousness and can-you-believe-thisery.


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