Jill Weisleder/Los Angeles Dodgers

By Cary Osborne

When I was a kid, I had baseball books filled with stats and rankings of the greatest baseball players of all time.

The numbers fascinated me at an early age.

But this was a time when the most advanced statistic listed in those books was on-base percentage. Not even a WHIP here or an OPS there. It was your basic home runs, batting average, win-loss and ERA stuff.

So in a very rudimentary way (I remember being 12 years old or so at the time), I ranked who I thought were the greatest baseball players of all time, based off these numbers and some mathematics on my own part.

I determined it was Ted Williams, followed by Babe Ruth and Hank Aaron.

Pretty good choices I’d say.

Some 20-plus years later, with Baseball Reference at my disposal, I decided to try this exercise in a similar way all over again based off something I’ve witnessed the last five years.

After some deep number crunching, I’ve come to the conclusion that Clayton Kershaw’s span from 2011–2015 is one of the five greatest five-year pitching runs of the last 100 years.

To me, the most telling pitching statistics have always been — even with new metrics — ERA and WHIP. WHIP tells me just how dominant a pitcher is. It tells me how good a pitcher is at keeping men off base. Less men on base, less opportunities to score. And the point of baseball is to score more runs than the other team. Hence, the measurement of runs allowed per nine innings has always been the golden stat for me in measuring a pitcher.

So using that golden stat as a starting point, I took Kershaw and compared him to pitchers of his era, his age group historically and pitchers in their fourth to eighth seasons (which are Kershaw’s 2011–15 seasons).

The next step for me was measuring him among the greatest five-year spans for left-handed pitchers in the Live-Ball Era (post-1920). Lastly, I put his five years against the greatest such time spans since 1914.

I also included other measurements that tell me about control/command (SO/BB ratio), dominance over hitters (SO/9 innings), innings pitched (which Kershaw has said is one of the most important stats to him) and two advanced stats — WAR and ERA+.

The last five years.

It’s not even close. Kershaw has been MLB’s best pitcher across the board. These five pitchers have the best overall ERA between 2011–15. The qualifier here is that a pitcher had to pitch all five seasons.

Ages 23–27

Kershaw’s extraordinary run began when he was 23. Many great pitchers begin dominant runs at young ages, so I wanted to see how Kershaw compared to pitchers in his age group. Baseball Reference, through its play index, will do that grouping for pitchers since 1914. Kershaw had the best run ever from ages 23 to 27 (and ERA+ is the most telling stat that determines that judgment because it compares pitching performance to the league average, with 100 always being the league average).

Seasons 4–8

The next thought was to see how Kershaw compared to other pitchers, also since 1914, in their fourth to eighth season in the big leagues. It could be argued here that Kershaw is also the best in this category again because of ERA+ alone. The fact that he is even up there with Grover Cleveland Alexander, who won 373 games and ranks fourth all-time in WAR for pitchers, is incredible.

Left-handers

Who is the greatest left-handed pitcher of the Live-Ball Era? Lefty Grove, Sandy Koufax, Randy Johnson, Warren Spahn and Carl Hubbell could all make the argument. Kershaw is among that group of left-handers in that just eight lefties have had a WAR of 34.0 or above in a five-year period.

Since 1914

I recently read this article by ESPN’s David Schoenfield in which he wrote about the best five-year peaks for pitchers since 1950. Why 1950?

“I started with pitchers since 1950, primarily because I’m not as interested in comparing the peak of Dead-Ball era pitchers to the more modern game. Plus, we had to make this somewhat manageable,” he wrote.

With that being said, 17 pitchers since 1950 have had a five-year stretch where their combined WAR was 35.0 or over. I’ve given you the top 10 with Kershaw in that group. He actually ranks 15th overall in WAR. Nos. 11–17 are: Wilbur Wood (1971–75: 39.1), Juan Marichal (1962–66: 37.1), Kevin Brown (1996–2000: 36.9), Curt Schilling (2000–2004: 36.5), Fergie Jenkins (1968–72: 36.8), Kershaw, Johan Santana (2004–08: 35.4) and Bert Blyleven (1971–75: 35.2).

No pitcher who threw at least 750 innings in a five-year span in the 1920s, ’30s or ’40s had a better five-year ERA and ERA+ than Kershaw.

Between 1915–19, two pitchers had better ERAs and comparable ERA+ marks — the aforementioned Alexander and arguably the greatest pitcher of all time Walter Johnson.

Among all the pitchers listed in this story, Kershaw ranks sixth in ERA, right behind Koufax. He is third in WHIP — Martinez: 0.9256, Koufax: 0.9259, Kershaw 0.933. Kershaw is fifth in ERA+. He’s second to Pedro Martinez in SO/BB ratio. He’s also third in SO/9.

I’m convinced, Kershaw is top five over the last century.

How about you?