Saturday, December 30, 2006

Translation of Zone Rating into Runs Saved

In Part 1 of my 2006 fielding analysis, I ranked the Tigers on range factor and zone rating. Range factor is not so useful now that more sophisticated measures are available. Zone rating is still regarded as one of the better measures and it’s also very accessible throughout the year. Several attempts have been made to translate Zone rating into runs saved. One of the most cited methods was developed by Chris Dial who writes for Baseball Think Factory.


Dial compares each players zone rating to the average for other players at his position and then estimates the approximate run value of a ball in play at each positions. From that, he determines the runs saved a player aggregates above or below the average player at his position. In the tables below, RS= total runs saved above average and RS/150 = runs saved above average based on 150 games. The second measure allows us to better compare players with different numbers of games played.


The resulting ranks are slightly different from the zone rating ranks. This is because he does the American League separately from the National League. Zone rating, on the other hand, does not differentiate between leagues. The reason he separates the leagues is because, with pitchers batting in the National League, there are more softly hit balls and this creates somewhat of a bias.


Table 1 shows how the Tigers ranked compared to others at the same positions on RS and RS/150. According to this statistic, Placido Polanco saved 21 runs more than the league average based on 150 games played. Brandon Inge was 20 runs above league average. Those are impressive numbers. Theoretically, each is worth 2+ wins compared to the average player with their fielding over 150 games. Chris Shelton also ranked high (17 RS/150 games) topping all first basemen in baseball on this statistic. The only Tiger regular who fell below the league average was Magglio Ordonez (-2 runs per 150 games).



Table 1: Runs Saved by Tigers Fielders in 2006.


POS

Player

#

ZR

ZR Rank

RS

RS Rank

RS/150

RS/150 Rank

1B

Casey

27

.871

4

4

6

6

4

1B

Shelton

27

.913

1

12

1

17

1

2B

Polanco

29

.881

2

14

2

21

2

3B

Inge

30

.825

2

20

1

20

2

SS

Guillen

30

.832

15

2

13

3

13

LF

Monroe

28

.855

18

1

15

2

14

CF

Granderson

27

.886

10

5

10

6

9

RF

Ordonez

27

.864

17

-2

17

-2

17

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