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kERA revisited- Phillies Starters and Volatility.

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Just a little bit volatile... via media.trb.com

 

This afternoon, Cliff Lee started July with a performance that was as ugly as his June was beautiful. When Lee imploded in the eighth, it was sudden and traumatic- 4 runs went on the board in the blink of an eye, turning a narrow lead into an almost sure defeat. This got me thinking about just how volatile Lee is- when he is good, he is amazing (as he was in June) when he is off, he falls apart just as spectacularly. He is in many ways the pitching equivalent of the little girl with the curl right on the center of her forehead. 

 

Last June, David S. Cohen created the kERA, or Kendrick ERA stat in response to Kyle Kendrick's volatility- to that point in the season, he had been either very bad, or very good, with almost no in between. He developed this stat by taking the difference between the pitcher's ERA in the best half of his starts, and his ERA in the bottom half of his starts. At the time, the group thought was that the better the starter, the more a smaller kERA would be desireable, as for lesser pitchers, the volatility would make it so that some of their starts would still be very winnable. 

With that in mind, I looked at the Phillies starters to see how their ERAs, kERAs, and win-loss records fit together. For the purposes of this writing, I looked at every Phillies pitcher to start a game (with the obvious small sample size warnings for pitchers not named Hamels, Halladay or Lee). The results are after the jump. 

 

 

Pitcher

Starts

Overall ERA

Good Starts

Bad Starts

kERA

Record

Team Record in his starts

Roy Halladay

18

2.44

1.03

3.92

2.89

11-3

15-3

Cliff Lee

18

2.92

0.50

5.86

5.36

9-6

11-7

Cole Hamels

17

2.41

0.70

4.42

3.71

9-4

11-6

Roy Oswalt

13

3.79

1.85

6.40

4.55

4-6

5-8

Vance Worley

7

2.29 (2.61)*

0.61

5.34

4.73

3-1

5-2

Joe Blanton

6

5.50

2.45

8.80

6.35

1-2

3-3

Kyle Kendrick

6

3.81 (4.80)*

0.60

9.00

8.40

2-2

3-3

* Vance Worley and Kyle Kendrick's overall ERAs include relief innings. Their ERAs as starters are indicated in parenthesis.

Unsurprisingly, Cliff Lee had the largest kERA among the four aces, almost a run higher than Roy Oswalt's. At his best, he has been the best pitcher on the team in terms of runs allowed, allowing half as many as Roy Halladay. But taking only his worst starts into account, his 5.63 ERA would tie him with J.A. Happ at 61st of 62 NL qualifiers.

More amazing, however, was Roy Halladay- while he has not had the eye-popping games Lee has (no complete game shutouts, and a higher average for his good starts), his bad starts still average up to be only slightly below league average. This is what makes him the ace of this team- his dependability. He was only truly awful once (and that was aided by a stellar relief performance by David Herndon). 

While evaluating the three aces on this team is a very small sample size, it seems that for aces, unlike their lower in the rotation counterparts, consistency brings better results. 

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