I like to think of SwStk% as a good proxy for the quality of a pitcher’s repertoire. So I thought it would be interesting to take a look at the top five pitchers who have seen their SwStk% increase the most since 2010. Whether it is due to a jump in velocity, better location, added movement, or a change in pitch selection, a rise in the metric is usually a sign that the pitcher will enjoy more success, or at the very least, a higher strikeout rate.
Zack Greinke has posted his first SwStk% above 10% and sure enough, his K/9 is easily at a career best of 10.7. Of course, we all know his story in terms of luck and his ERA is well above any of his ERA estimator metrics. He has thrown his fastball a bit less than in previous years, while throwing his curve ball the most he has since 2004. His slider usage has rebounded after a drop off last year. These factors likely have contributed to the spike in SwStk%, but also the move to the National League must be taken into consideration. Obviously, facing the pitcher around two to three times a game will help boost a pitcher’s SwStk%. Though the rise in SwStk% does look legit, I think the strikeout rate is a little too high, not quite matching the strong, yet not spectacular SwStk%.
Matt Garza is in a similar boat as Greinke. His strikeout rate has shot up on the heels of a career best SwStk% and the first time it has been over 10%. He has come over from the American League as well, but some bad luck, though not as bad as Greinke has experienced, has hurt his ERA. His 9.3 K/9 matches up much better with his SwStk%, and looks more sustainable as a result. Looking at his pitch selection, his fastball usage has dropped nearly 20%, as he has thrown all three of his other pitches more frequently, most notably his slider. This would certainly seem to benefit his SwStk% and resulting strikeout rate. In addition, his fastball velocity has increased to its highest mark since 2007, which is another contributing factor. As long as he continues mixing his pitches in this way, Garza should be able to post another season punching out about a batter per inning.
When your SwStk% was only 5.5% last season, it is not as difficult to find your SwStk% jump enough the following year to get onto this list. That is what John Lannan is finding, as his 7.7% SwStk% is actually a career high. That has not quite translated to his strikeout rate, as his current 5.2 mark still trails behind his 2008 mark of 5.8, but it is an improvement over last year’s miniscule 4.5. Lannan has benefited from a velocity spike, as his fastball now averages a career high 89.9 miles per hour, more than a mile per hour faster than last year. He has also been throwing his slider more and seen his change up usage increase by the smallest of margins, but still good for a career best. Given Lannan’s still below average velocity, his lower reliance on the fastball has to be a good thing for his ability to induce swinging strikes. If the increased velocity sticks, Lannan should be able to sustain the increased SwStk%, and might see another bump up in his K/9 next year.
Like Lannan, Doug Fister posted a rather pathetic SwStk% last year at just 4.4%, so it is no surprise that just a 6.4% mark got him into the top risers this season. A 1.4 mile per hour uptick in fastball velocity and more sliders and curve balls thrown at the expense of his fastball has certainly helped Fister induce more swinging strikes. He still remains well below league average in the SwStk% category, but that just means there is some opportunity to further improve his stuff and gives him some strikeout rate upside. With excellent control and an average above GB%, he will need to improve that K/9 again to avoid watching his ERA regress back towards his SIERA and xFIP marks next year.
Livan Hernandez has posted his best SwStk% since 2004, which is pretty amazing for a 36 year old who averages just 83.9 miles per hour with his fastball. But that velocity is exactly what has led to the increased SwStk%. Wisely, Livan has thrown his fastball less than 50% of the time for the first time since FanGraphs has pitch type data for, which is a big drop from last season’s 61.4%. Instead, he has thrown his slider, curve ball and change-up more often, which has to be more difficult for batter’s to make contact with than that batting practice fastball. It is actually pretty remarkable that all these seasons Livan has been throwing an 84.0 mile per hour fastball 60% of the time, but I guess his ERAs have confirmed that this was not exactly the best strategy.