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Potential Starting Pitcher K/9 Risers Through the Lens of SwStk%

A couple of weeks ago, I looked at the SwStk% metric and its relationship to K/9. In that article, I looked at pitchers in 2010, comparing their SwStk% and K/9 rates to determine who may be in line for a bump in strikeout rate in 2011 and who might be set for a decline. With a month now in the books, let us check in on some of the leaders in SwStk% who currently have a lower K/9 than might be expected.

Hiroki Kuroda was on last season’s list of pitcher’s whose SwStk% was higher than his K/9 suggested and he now tops this list for 2011. This may mean one of two things: there is something else not being fully captured by just SwStk% that is keeping Kuroda’s K/9 down, or Kuroda’s true talent truly is for a higher K/9, which will soon manifest itself. Sure enough, StatCorner tells us that his ClStr% (called strike percentage) is consistently below the 17% league average rate. Since called strikes count as a strike just as swinging strikes do, then that will certainly hurt his strikeout rate potential.

Funny that James Shields find himself on this list after I used him as an example of why K/9 could sometimes be deceiving of a pitcher’s true strikeout ability. This season, Shields has posted a career best SwStk% so far and has enjoyed some fantastic results. If we throw out his second start of the season where he somehow managed to not strike out any White Sox hitter (I am NOT normally a fan of simply throwing out a start by the way), Shields’ K/9 would jump to 8.7, which is more in line with that strong SwStrk%. What may be contributing to this increased SwStk% is a change in his pitch mix. According to PitchF/x, Shields is throwing his two-seamer less frequently in favor of his change-up and curve ball. This is a major positive as he has generated swinging strikes at a significantly higher rate with these two pitches, compared to his mediocre fastball.

Ricky Nolasco‘s SwStk% has remained in a tight range between 9.9% and 10.5% since 2008. In the past, his strikeout rates have been pretty strong, matching up with those SwStk% marks, so this does not appear to be a Hiroki Kuroda situation. Expect Nolasco’s strikeout rate to rise, but slight caution is warranted as his fastball velocity is down nearly one mile per hour from last year.

Jhoulys Chacin‘s SwStk% is down one percentage point from last year, but his K/9 has dipped over two points. His minor league strikeout rates were just okay, and certainly not high enough to suggest he is capable of punching out a batter per inning like he did with the Rockies last year. I think his SwStk% does hint at an improved K/9 though, probably to around the 8.0 range. In fact, ZiPS projects an 8.1 K/9 through the rest of the season, which is a reasonable expectation.

I know many fantasy owners are wondering about Jeremy Hellickson, especially since I have been rather optimistic about his potential this year. With a 4.31 ERA and 4.45 xFIP, he has been a disappointment so far. There is some real good news, however. Aside from the strong SwStk%, he has gotten called strikes well above the league average. When you look at both his SwStk% and ClStr% in tandem, these levels typically match up with striking out at least a batter per inning. As a result, I think he has some pretty significant K/9 upside and would therefore make a good trade target. Of course, the nearly 46% FB% is a concern, but an increased K/9 and better control more in line with past seasons should easily push his ERA below 4.00.