What to expect through Kershaw's contract

Rob Leiter/MLB Photos via Getty Images

Clayton Kershaw has led the majors in ERA in each of the last three seasons.The Los Angeles Dodgers have invested heavily in Clayton Kershaw, reportedly giving the two-time Cy Young Award winner a record-setting $215-million dollar contract.

For more on Kershaw’s performance, check out yesterday’s blog post on his accomplishments and how it compares to other legendary pitchers at his age.

But the now the question shifts to how Kershaw will age and perform over the length of his seven-year contract.

In order to do that, we need to look at the pitchers who have fit a criteria similar to Kershaw at this point in their careers:

• At least 900 innings pitched from age-20 season to age-25 season

• An adjusted ERA (ERA+) of 120 or better over the span (ERA+ allows us to accurately compare pitchers across different eras)

• Pitchers who began their careers in 1950 or later

Using that criteria, we get 20 pitchers to whom we can compare Kershaw (those who have pitched at least through their age-32 season, since this contract would take Kershaw through his age-32 season). Here are the main takeaways:

Innings and Durability

It’s inevitable to expect pitchers to have an innings drop-off as their careers go on.

That being said, the 20 pitchers who have a criteria that most closely matches Kershaw averaged 236 innings pitched in the year prior to turning 26. That average dropped to 179 innings pitched by their age-29 season, and 121 for the age-32 season.

Among the 20 pitchers, only four pitched at least 175 innings each year through their age-32 season: Tom Seaver, Jim Palmer, Dave Stieb and Mark Buehrle.

There were twice as many pitchers who threw under 100 innings in their age-32 season (eight) than there were who pitched at least 200 (4).

Quality of Performance

The 20 pitchers posted a cumulative 2.96 ERA in their age-25 season, and about the same number the next year.

Best Adjusted ERA in Live Ball Era
Through Age-25 Season

And while the performance predictably dropped off through the years, the group never put up a much worse ERA average. The highest total ERA among the group was a 3.59 ERA in their age-31 season.

However, the innings decrease did negatively affect their production. The best way to measure this is to use Wins Above Replacement.

The group of 20 put up a WAR of between 4.8 and 4.9 in each season from age-25 to age-27. In the next three years, that mark fluctuated from 3.9 to 2.9, and dropped to 2.5 or lower in the age-31 and age-32 seasons.

For perspective, Kershaw posted a 7.8 WAR last season, and has had at least 4.7 WAR in each of his last five seasons.

Average Yearly Production
of 20-Player Sample


By the seventh season, what would be the final season of Kershaw’s extension, 35 percent of the sample of 20 pitchers was essentially replacement-level, while only 20 percent produced what would be referred to a star-level performance.

If Kershaw follows the trajectory of the 20-player sample, the chart on the right shows what could be reasonably expected of him throughout the contract.