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Introducing a New Stat: The Kendrick ERA (kERA)

Kyle Kendrick did it again last night.  As I noted in the introduction to the game thread, he's been maddeningly inconsistent this year.  Or, actually, he's been quite consistent, just in two different ways.  I wrote:

Kendrick has had a true Jekyll and Hyde season so far.  In five of his starts, he's been phenomenal, posting a 0.75 ERA in 36 innings.  However, in his other seven starts, he's been absolutely atrocious, posting a 9.76 ERA in 31.3 innings.

Well, last night, Dr. Kyle Jekyll showed up, as he was excellent once again.  He gave up 1 run in 7 innings, holding the Yankees to 4 hits and 2 walks.  After last night, his bad seven starts remain at a 9.76 ERA, but he now has six good starts for a 0.84 ERA.  He's been so good in his good starts, that giving up just 1 run in 7 innings last night actually made his good-start ERA go up!

Kendrick's split personality this year got me wondering about other starters of his quality, so I decided to take a look.  For the year, Kendrick has a 4.48 ERA.  There's a nice grouping of 20 starters who I consider roughly comparable to him so far this year, with ERAs between 4.21 and 4.71.  With ERAs in the mid-4s, these starters are neither world-beaters nor slop-throwers.  Going by ERA+, they're just below average, as ERAs in this range are in the 90s for ERA+.

What I decided to do was calculate each starter's kERA, or Kendrick ERA.  kERA is the difference between the ERA for the top half of the starter's games versus the bottom half.  Kyle Kendrick himself sports a whopping 8.93 kERA.  Is anyone besting him at his own game this year?

Turns out, the answer is yes, but just slightly.  Here's a chart of these 20 starters ranked by kERA, from highest to lowest:

Joe Saunders 4.70 8.97
Kyle Kendrick 4.48 8.93
Joel Pineiro 4.45 8.54
A.J. Burnett 4.33 7.77
Bronson Arroyo 4.53 7.03
Mark Buehrle 4.71 6.79
Nate Robertson 4.57 6.54
Felipe Paulino 4.50 6.11
Dave Bush 4.67 6.05
Dan Haren 4.71 5.79
Johnny Cueto 4.50 5.77
Mitch Talbot 4.21 5.75
Scott Baker 4.41 5.30
John Lackey 4.53 5.26
Chad Billingsley 4.34 5.10
Rodrigo Lopez 4.70 4.94
Gio Gonzalez 4.21 4.79
James Shields 4.55 4.43
Chris Volstad 4.25 4.33
Kenshin Kawakami 4.42 4.18

Joe Saunders is the leader here, posting an 8.97 kERA.  In Saunders' 7 top starts, he's posted a 1.22 ERA over 51.67 innings.  In his 7 horrible starts, he's posted a whopping 10.19 ERA in 32.67 innings.  With that kind of spread, he's our leader in kERA.

On the other end of the spectrum is Kenshin Kawakami.  His 4.18 kERA leads this group, showing that he's been pretty consistent on his way to his unlucky record of 0-9.  In Kawakami's six best starts, he has a 2.27 ERA.  In his 7 worst, he's got a 6.45 ERA.  He's rarely dominant, but also rarely atrocious.

Without going further into analysis, I'll pose a question for discussion.  For starters in this ERA range, which would you rather have: A starter with a high kERA, who is either dominant or horrendous, but never in between; or a more consistent starter, one with a lower kERA, but who never truly sparkles?