Sunday, February 5, 2012

Jeff Karstens's Crazy June and July

On the surface, Karstens had a heck of a year last year.  The 28 year-old finally saw significant action in the rotation and responded with a 3.38 ERA.  Amazingly, Karstens could have had an even finer year had he pitched the entire season in the same manner he pitched the middle of the season.  Specifically, Karstens turned in a wonderful June and July, at least on the surface.

In June, Karstens started six times and only gave up seven earned runs in 41.1 innings for a phenomenal 1.52 ERA.  In July, he continued his success, giving up eight earned runs in 35 innings over five starts for an ERA of 2.06.  However, as I keep repeating, that's on the surface, so let's dig deeper.  June was Karsten's best month by ERA, so it's surprising to see it was also his worst month when gauged by his xFIP of 4.69.  July was his second best month by ERA, but again it was a bad month according to Karsten's 4.21 xFIP.  Basically, for two months, Karstens got extraordinarily lucky, at least as told by advanced metrics.

Looking at Karsten's strikeout rates alone, it is amazing that his June and July were so successful.  In March, April, May, and then August, the starting pitcher's strikeout rate stayed consistent, between 7.0 K/9 and 8.0 K/9.  However, in both June and July, that number dipped dramatically to 3.27 in June and 3.60 in July.  Read that again: Karsten's lowest K/9, which was an abysmal 3.27, came in a month in which he gave up one-and-a-half runs per nine innings.  His second lowest K/9 came in his second best month.  During those two months, Karstens also posted great BB/9 numbers, around 1.5 BB/9 for each month, but Karstens actually walked less batters in May.

Karstens's groundball numbers were on par with what he did all year in the months of June and July.  In July, Karstens was very lucky when it came to home run percentage, benefiting from only 4.9% of flyballs hit against him going over the fence.  The 10.5% in June was basically average for the year.  In addition to his home run luck, Karsten's great ERA in July was fueled by an above-average 79.8% LOB rate and a .261 BABIP.  However, both numbers aren't that far removed from the mean to be that incredible in a small sample size.  Basically, in July Karstens was the beneficiary of solid luck in a number of categories and from his ability to only walk six batters in 35 innings.

So what about June? In June, Karstens simply got unbelievably lucky.  Look no further than his strand rate and his BABIP.  For the month, batters only got a hit 17% of the time they put the ball in the field of play against Karstens for a total average of only .186 despite the extreme lack of strikeouts.  Still, that BABIP isn't as amazing as Karsten's strand rate. In June, the pitcher stranded 97% of base runners he allowed.  Considering he allowed 34 base runners, that means only one scored. That also means, Karstens gave up six solo home runs.

Basically, Karstens probably couldn't have gotten any luckier in June.  Cynics, myself included at times, would knock Karstens for that.  However, as a fan, I simply preferred the ride. I know my fantasy team did.  Now, let's hope Karstens can continue his luck in 2012.

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