At age 20, Randy Johnson was a year away from being a fourth round pick in the 1985 MLB Amateur Draft. Roger Clemens was working successfully between A and AA ball in Boston's farm system. Pedro Martinez recorded an 0-1 record in just eight innings of work in the Majors.
More recently, a 20-year-old Tim Lincecum was two years away from his minor league debut. Between AA and AAA, a 20-year-old Roy Halladay compiled a 4.77 ERA with just a 1.47 K/BB ratio over 162 innings.
I gave you that information as a point of reference for this:
As a 20-year-old pitcher, Clayton Kershaw threw over 100 innings as a starter for the Dodgers. He certainly had his struggles, but he struck out over eight batters per nine innings. His ERA+ of 98 placed him right near league average for starting pitchers.
At age 21, Kershaw led the league in fewest hits allowed per nine. His 1.22 WHIP and 2.91 ERA gave him a well above average 143 ERA+ (a ballpark adjusted stat that scales the league average ERA to 100), and he struck out more than a batter per inning.
At age 22, he did more of the same. Over 204 innings pitched, he again posted a very good ERA+. For the second time in his first two full seasons, his standard ERA was below three. Again, he struck out over a batter per inning and took major strides toward improving his control.
When looking at a player's development, age relevancy is a big deal. Kershaw was performing well above league average at an age when most elite pitchers hadn't even sniffed the big leagues. The seventh overall pick of the 2006 draft, he has always been a prized prospect. Most of the time, teams are more careful about moving these types of pitchers along given their investment in a position with such high rate of attrition.
Kershaw rightfully earned the right to advance so quickly.
I hinted earlier that he had some control issues in the early part of his career. In both 2008 and 2009, he walked more than four batters per nine innings. As an extremely young pitcher working against major leaguers, though, this is to be expected. Last year he brought that number down to 3.6.
With such vast improvement in his one and only weak area, I fully expected Kershaw to continue his improvement and step into his own class of pitchers this season. On stuff alone, he's always had the potential to do so. His fastball moves a lot and sits consistently at around 94 MPH. He doesn't rely on it near as much as he used to, but his curveball may be baseball's nastiest pitch when it's on.
Though his play has been worthy of the national media's attention over the past few years, I expected this year to be the one when he'd start performing at such a high level he could no longer be ignored. It seemed reasonable to expect less than three walks and between nine and 10 strikeouts per nine innings and an ERA under 2.50.