Wednesday, January 09, 2008

Outfield Arms - 2007

This is the eighth part of my series on fielding in 2007. The table of contents for the entire series is listed below:

Basic fielding stats
Converting Zone Rating to something useful
Revised Zone Rating
Probabilistic Model of Range
Fielding Bible
Ultimate Zone Rating
Fan Fielding Survey versus range measures
Outfield arms
Ranking the second basemen
Ranking the shortstops
Ranking the third basemen
Ranking the first baseman
Ranking the center fielders
Ranking the right fielders
Ranking the left fielders
What about catchers?

Earlier this week, John Walsh - a writer for The Hardball Times - wrote his annual report on outfielder arms. With the exception of the Fan Fielding Survey, all the measures that I have discussed in this series have focused on an outfielder's ability to catch fly balls. That is the most important part of outfield defense but the ability to stop the running game by throwing runners out or preventing them to advance is also important.

Using the the retrosheet database, Walsh considered any situations where a runner had a chance to take an extra base on a ball hit to the outfield (e.g. single with runner on first and second base unoccupied). For each outfielder, he counted the number of advancement opportunities, the number of times he threw a runner out (kill) and the number of times he prevented a runner from advancing (hold). From this, he determined how the outfielder compared to league average in each category. Then, using the run expectancy matrix (e.g how likely is it for a run to score with a man on first and third and no outs compared to a runner on first and one out), he then calculated runs saved above/below average for each outfielder.

The results for the Tigers in 2007 are on Table 1 below. Using Curtis Granderson as an example, the table reads as follows: There were 222 opportunities for runners to take an extra base on Granderson's arm in 2007. His kill+ ratio (99) says that he was 1% below the average center fielder in throwing out base runners. His hold+ ratio (100) says he was exactly average. Walsh estimated that Granderson prevented 1.1 runs above average per 200 opportunities (or approximately a full season) with his arm.

I then came up with the Range Runs column by taking the average of the five RSAA/150 estimates discussed earlier in the series. In Granderson's case, he prevented 19.8 runs above average with his range. The final column is the sum of the Arm Runs/200 opps (which is roughly equivalent to 150 games) and Range Runs/150 game columns. We can see that all three Tigers outfielders finished above average in 2007.

New Tigers outfielder Jacque Jones finished off the charts at 35.9 runs above average thanks to outstanding numbers on both arm and range. He had a good year defensively with well above average range scores on all range metrics and 8 assists in 76 opportunities. However, I think magnitude of the final result is partially the result of a relatively small sample size (645 innings).

Table 1: Runs Saved Above Average (per 150 games) for Tiger Outfielders in 2007.

Pos

player

Opps

Kill+

Hold+

Arm Runs/150 games

Range Runs/200 opp

Total Runs/150 games

LF

Monroe

103

154

106

4.3

1.3

5.6

CF

Jones

76

321

99

13.7

22.2

35.9

CF

Granderson

222

99

100

1.1

20.0

21.1

RF

Ordonez

142

58

108

-1.8

3.9

2.1

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