Tonight, Stephen Strasburg returns to a major league mound. With his 2011 debut comes a reminder that this 22-year-old represents a major change in the way baseball has been played; a shift that, year after year, has meant more and more emphasis on strikeouts as a way to set the opposition down.
Pitching continues to evolve, as hurlers are always searching for new and better tools to use against hitters. In part because of this, strikeout rates that were considered average 25 years ago are considered poor today. In 1986, just 19 of the 80 pitchers who qualified for the ERA title struck out more than the 2011 league average. Of the 100 pitchers who qualify in 2011, 46 are above the 2011 league average, and 72 are above the 1986 average.
Back in 1986, six strikeouts per nine innings would get you the "league average" designation. Today, you need seven per nine to do that. There has been a gradual shift each year, with the last three seasons the only ones at or above seven strikeouts per nine, dating all the way back to 1871. Just two of the top 20 seasons all-time for strikeouts per nine occurred outside of the last 20 years -- and the fairly recent year of Strasburg's birth, 1988, isn't one of them:
The '67 season came just two years before the mound was raised in order to give the hitters a fighting chance (and that mark stood alone for 20 years). That season and '87 used to be more impressive, but now they look pedestrian compared to the last decade.
Looking at individual pitchers tells the same story. Most of the top five in K/9 (minimum 1,000 innings pitched, and 60 percent of the innings as a starter) are predictable: you've got Randy Johnson as the all-time leader at 10.6 per nine, then Pedro Martinez in second as the only other pitcher over 10 K's per nine. The Big Unit and Pedro haven't raised the league-average strikeout rates on their own, of course: Tim Lincecum, with 1,001 career innings, is third with 9.95 per nine. Johan Santana (9.0) is eighth, and Jake Peavy (8.8) is ninth. Curt Schilling (8.6), Roger Clemens (8.6), Cole Hamels (8.5) and Josh Beckett (8.45) are also modern pitchers within the top 15.
None of those pitchers are very surprising, as they, at their best, are some of the best hurlers many of us have seen in our lifetimes. In today's game, though, you don't need to be a good pitcher to strike hitters out. Scott Kazmir was pretty good for Tampa Bay for a few years, but was never considered an elite starter. Yet here he is, 10th all-time in K/9. A.J. Burnett is 21st, punching out 8.2 per nine. Hideo Nomo was great for Los Angeles for a few seasons, but he finished his career with a below-average ERA+. Despite this, he's 11th in career K/9. Matt Clement is 29th, Chan Ho Park is 30th, Wandy Rodriguez is 31st, Jason Bere is 44th... the list goes on with pitchers who had their moments, but, in the eyes of history, are just not considered great.
The example that does the best job of explaining this trend for high strikeout rates extending beyond just the game's best has to be Oliver Perez, though. Perez, who was nearly 10 percent worse than average by ERA over his career, and walked more hitters than he struck out before possibly pitching himself out of the league in his final 100-plus innings, ranks sixth in K/9.
Nolan Ryan and Sandy Koufax are both in the top five, but their presence just reminds you how ahead of their time they were. In today's game, they would still be great, but they may not be the giants they are now considered to be, simply due to the relativity of it all. Strikeouts happen so often now, it's easier to take them for granted than it once was. With Strasburg back -- the same Strasburg who struck out 12.2 per nine in his rookie 2010 campaign, and has punched out 11.2 per nine as a minor leaguer -- it's going to be even easier. He's special, though, even within the context of today's strikeout-happy game. And, like Lincecum, Pedro, Randy Johnson, and others like Ryan and Koufax before him, he's representative of the entire league's progress on the mound.