ERA and Defense


I have been doing 2011 fantasy profiles for the Royals for Fangraphs and the Hardball Times.  I kept seeing a pattern of Royals pitcher's ERAs being higher than their true talent suggests (FIP and xFIPS).  Here are the lifetime numbers for 4 starters that spent most of their major league careers in KC:

Name ERA FIP xFIP
Hochevar 5.60 4.47 4.46
Davies 5.49 4.93 5.04
Greinke 3.82 3.59 3.91
Bannister 5.08 4.77 4.86

 

Besides Zack' s xFIP, all four of the pitcher's ERA were higher than their FIP and xFIPS.  It wasn't just limited to these pitchers, here are the team numbers for the past 3 years:

Year ERA FIP xFIP
2010 4.97 4.48 4.59
2009 4.83 4.36 4.44
2008 4.50 4.21 4.42

 

In 2008 there was not much difference in the values, but in 2009 and 2010 the team's ERA was close to a half run higher than FIP or xFIP.  Part of this discrepancy can be blamed on the team's defense. 

The years with the largest decrepancies are the same years the Royals have the worst defense according to their UZR numbers.  Here on the team UZR totals over the past three years:

Year Team UZR
2010 -44.5
2009 -49.1
2008 -10.2

 

I expanded study and did the UZR-ERA relationship for all teams and the relationship holds (I will post the results on Fangraphs in a few days).

Using the 2010 value of -44.5 runs, divided into 162 games equals -0.27 runs per game.  According to UZR, the Royals defense gives up about a quarter point per game.

What does all the previous rambling mean:  The Royals defense has been so bad the past couple of seasons, that they have helped to inflate their pitchers ERA's from 0.25 to 0.50 points.  With the team's defense probably not being much better in 2011, remember that the defense needs to be also blamed for the pitcher's struggles as the season goes on.

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