Top 5 SwStk% Decliners by Mike Podhorzer October 24, 2011 On Saturday, I examined the five pitchers whose SwStk% increased the most from 2010. Today, I will look at the opposite: the five pitchers whose SwStk% declined the most this season. After never posting a strikeout rate above 8.6 in the Minors, Jhoulys Chacin surprised many when he struck out about a batter per inning during his 2010 rookie season. That K/9 was supported by an excellent 10.8%. Unfortunately, the fun couldn’t last, as both his strikeout rate and SwStk% dropped precipitously this past year. He threw his slider more frequently, primarily at the expense of his curve ball and change-up. Normally, that would have been a favorable change in pitch mix. However, the whiff rate on both his curve and change dropped significantly enough to offset any positive impact of throwing more sliders, which generated the best whiff rate of all his pitches. Given his minor league performance and the fact that his 2010 SwStk% was likely inflated a bit due to his relief appearances, I think his true talent is closer to his 2011 results. I think we will see improvement though in his K/9 next year, with a rebound back into the 7.5-8.0 range. Funny, Jered Weaver posts the best ERA of his career, yet his SwStk% dropped to its lowest mark since 2007. Of course, that shouldn’t surprise anyone since his K/9 fell back to where he sat in 2008 and 2009. It looks pretty clear now that 2010 was the outlier. Whatever magic he conjured up last season, it is unlikely to return. I would not be expecting a 2012 strikeout rate somewhere between his 2010 and 2011 marks. Some might, and combined with his significant outperformance of his SIERA (yes, he typically outperforms, but never to this degree), he will almost certainly be overvalued in drafts next year. Daniel Hudson’s short time with the Diamondbacks really inflated expectations this year. He posted a 12.3% SwStk%, which was naturally unsustainable. He even had some seemingly positive changes in his pitches this year, such as increased fastball velocity and more frequent usage of his slider, but that wasn’t enough to repeat that fantastic SwStk%. The good news is that a 9.9% SwStk% suggest much higher than a 6.9 K/9, and his minor league track record of excellent strikeout rates agrees that the upside is there. He will need to get more called strikes though as that looks to be one of the primary issues that explains the discrepancy between his SwStk% and K/9. Ricky Nolasco’s declining skills may be a boon for sabermetricians. We could finally stop drafting him on our fantasy teams! Nolasco lost some fastball velocity this season, and since it was only about average to begin with, it may have hurt the effectiveness of his breaking balls. The good news is that an 8.9% SwStk% still should match up with a higher K/9, at least above 7.0. If he recovers some of his lost velocity next year, he should rebound in the strikeout rate department. And now given three straight years of an ERA of at least 4.51, he may finally be banished from most sleeper lists and be had for cheap, if you dare. After enjoying a second breakout season as a starting pitcher in 2008, and having strong follow ups in 2009 and 2010, Ryan Dempster was a major disappointment this year. Although his SIERA and xFIP were nearly identical to last season, as was his strikeout rate, the drop in SwStk% suggests he has lost something. In fact, the only reason his K/9 was nearly as good as last year was because his BABIP was .324, giving him additional chances to punch out hitters. His fastball velocity dropped to its lowest mark during the time period FanGraphs has data for, though it was only a decline of 0.7 MPH from last year and 0.3 MPH from the previous one. He also threw his slider less often this year which had to have hurt his SwStk%. Dempster will be 35 for most of next season, so it isn’t too crazy to believe his stuff truly is diminishing. That said, he was quite unlucky any way you look at it and could very well be undervalued next year.