In a blog post on May 24, I introduced a measure for the determination of strikeout quality called the Actual vs. Expected Strikeout Ratio (AESR). You can see that post for a description of the calculation of the AESR. I have updated the AESR ratios for games through June 9, 2010. The updated top 10 in AESR ratio are shown below.
Tim Lincecum
Tim Lincecum still leads the list, even though he ranks just fourth in the major leagues in number of strikeouts per 9 innings. This is because of the 112 different batters that Lincecum has faced, he has struck out 61% of them more than the average pitcher based on the expected strikeout ratio of the batters. Of the batters he has struck out, he strikes them out an average of almost 2.5 times more than average. Of the batters that Lincecum has faced more than once, there are several batters that Lincecum had significant success against. Lincecum has faced Jorge Cantu three times this year and has struck him out all three times, although Cantu normally strikes out only once every six times at the plate. He has also faced Raul Ibanez three times and struck him out twice, even though Ibanez on average once every seven plate appearances. He has also been successful against Shane Victorino, striking him out twice in four plate appearances, although Victorino strikes out in just one out of every eight plate appearances.
Francisco Liriano
Francisco Liriano is a close second to Lincecum, and he ranks high for similar reasons as Lincecum ranks high. Liriano has faced 77 different batters this season, and has struck out 62% of them more than expected based on their average strikeouts per plate appearance. Of the batters he has struck out, he has struck them out on average about 2.3 times more than expected. Of the batters that Liriano has faced more than once, he has had significant success against a number of batters. Gabe Gross has struck out three times in three plate appearances against Liriano, even though on average Gross on strikes out in 18% of his plate appearances. Ramon Santiago and Mike Sweeny have both struck out twice in three plate appearances against Liriano, even though they both strike out on average in just 13% of their plate appearances.
Other Top 10 Pitchers
Of the other pitchers in the top 10 in AESR, Phil Hughes remains in the top 10 even though he does not rank in the top 10 in strikeouts per 9 innings. Adam Wainwright also makes the top 10 even though he ranks 18th in strikeouts per 9 innings.
Bud Norris
The interesting omission from the top 10 in AESR in the pitcher that ranks number one in strikeouts per 9 innings. The current leader is Bud Norris, who is striking out just over 11 batters per 9 innings, however he ranks 11th in AESR. The reason Norris ranks lower in this statistic is because of the 77 different batters he has faced, he has only struck out 49% of them greater than the expected number of times. Of the batters he has struck out, he strikes them out more than 2.5 times than average.
Stephen Strasburg
Stephen Strasburg made his major league debut on June 8th, and the expectations for Strasburg were greater for him than for any other major league debut. By most accounts, Strasburg did not disappoint in his debut. While it is only one game, I could not resist seeing how Strasburg’s 14 strikeouts ranked in terms of the AESR.
As can be seen in the table above, based on the average strikeouts per plate appearance, the average pitcher would have struck out just under five batters. Strasburg’s 14 strikeouts yield an AESR of just under 3, significantly higher than any other pitcher that has pitched at least 40 innings. He struck out all of the batter he faced at least once, and even struck out Lastings Milledge twice even though he strikes out normally only once every seven at bats. It will be interesting to see how his numbers develop as he has more starts and batters see more of Strasburg.
