Tango then tabulates the results which can be seen in detail on his site. Each player ends up with a score between 0 and 100 on each of the 7 skills. The league average rating for each of the 7 categories is 50 and a player with a rating of 70 or better is in top 16% in the league.
Tango
also has a method for turning these ratings into runs scored
above average. First, weighted averages are created for each player
based on the importance of the skills at his position. The weights are
shown on Table 1 below. I'm not exactly sure how he decided upon these
weights but they make intuitive sense. For example, a third baseman's
arm strength carries more weight than his speed. On the other hand,
speed and acceleration are very important for outfielders.
Table 1: Weights for skills on fan fielding survey
Pos
|
Instincts
|
First Steps
|
Speed
|
Hands
|
Release
|
Arm Strength
|
Accuracy
|
C
|
1.3
|
0.3
|
0.3
|
1.3
|
1.3
|
1.3
|
1.3
|
1B
|
1.6
|
1.6
|
0.4
|
1.6
|
0.8
|
0.4
|
0.4
|
2B
|
1.6
|
1.6
|
0.8
|
1.6
|
0.8
|
0.4
|
0.4
|
SS
|
1.5
|
1.5
|
0.7
|
0.7
|
1.5
|
0.7
|
0.4
|
3B
|
0.9
|
0.9
|
0.5
|
0.9
|
0.9
|
1.9
|
0.9
|
LF
|
1.0
|
2.0
|
2.0
|
1.0
|
0.5
|
0.3
|
0.3
|
CF
|
1.0
|
1.9
|
1.9
|
1.0
|
0.5
|
0.5
|
0.2
|
RF
|
0.9
|
1.9
|
1.9
|
0.9
|
0.5
|
0.5
|
0.5
|
Once
the weighted average is computed for a player, it is subtracted from the average score for all players at his position. Adjustments are then made to make it comparable to the distribution of the Ultimate Zone Rating (UZR) statistic which has a smaller standard deviation. For those who are interested in the details, the adjustments are explained in the comments here. I tried following that algorithm and got slightly different results (although very close) from what is listed on FanGraphs under FSR. The FanGraphs results are used in this post.
Remember that these observations should be based on skills rather than performance. So, Jackson's score says that, in the eyes of fans, he has the skills to be a center fielder who is +8 runs above average in 1,184 innings (his total for 2012). On the other hand, his +5 runs above on Defensive Runs Saved (DRS) is an estimate of his actual performance last year.
Table 2: Fan Scouting Report for Tigers, 2012
player
|
n
|
instincts
|
first
step
|
speed
|
hands
|
release
|
arm
strength
|
accuracy
|
FSR
|
|
C
|
Avila,
Alex
|
47
|
52
|
40
|
33
|
56
|
67
|
63
|
63
|
2
|
C
|
Pena,
Brayan
|
18
|
33
|
23
|
23
|
31
|
29
|
36
|
29
|
-4
|
1B
|
Fielder,
Prince
|
55
|
32
|
20
|
25
|
25
|
25
|
36
|
31
|
-6
|
2B
|
Infante,
Omar
|
47
|
70
|
65
|
61
|
63
|
65
|
49
|
63
|
+5
|
3B
|
Cabrera,
Miguel
|
62
|
49
|
30
|
27
|
48
|
47
|
79
|
58
|
-3
|
SS
|
Peralta,
Jhonny
|
56
|
46
|
32
|
36
|
62
|
59
|
51
|
61
|
-11
|
CF
|
Jackson,
Austin
|
61
|
84
|
88
|
86
|
79
|
65
|
45
|
55
|
+8
|
RF
|
Hunter, Torii
|
19
|
75
|
70
|
61
|
75
|
77
|
70
|
77
|
+7
|
RF
|
Boesch,
Brennan
|
52
|
10
|
23
|
38
|
11
|
22
|
45
|
35
|
-5
|
Table 3 compares the fan fielding estimate with other defensive measures. For the most part, the Fan Fielding results for the Tiger players correlate reasonably well with the advanced measures. Players that did well on the advanced statistics such as second baseman Omar Infante, center fielder Austin Jackson and right fielder Torii Hunter - were also given high scores by the fans. It should be noted though that Tigers fans rated Infante as average while Marlins fans had him well above average.
The fans and defensive statistics agreed that Miguel Cabrera was a a below average fielder, but his -3 on FSR was better than any of his other statistics. There was universal agreement that right fielder Brennan Boesch was a poor defender.
There was more disagreement on shortstop Jhonny Peralta than any other player. Peralta was rated worse by the fans (-11) than any of the advanced fielding measures. Even the defensive metrics did not come to a consensus with Peralta ranging from -6 on Baseball Prospectus' FRAA to +10 on UZR. There is some thought that DRS and UZR could be biased for some players due to human error in recording of location of batted balls. So, perhaps the lower scores on FRAA and RZR might be more reliable for Peralta.
Why might the fans score be lower than all the metrics? It could be that Peralta's skills were poor, but was able to perform above his skills for the year. In that case, we might be wary about his ability to keep it up in 2013. On the other hand, it could be that the fans are biased because he does not look athletic and that he's actually better than he seems. We may learn more this year.
Table 3: Comparison of Runs Across Different Fielding Measures
Player
|
FSR
|
DRS
|
UZR
|
FRAA
|
RZR
|
|
C
|
Avila,
Alex
|
+2
|
+6
|
---
|
-3
|
---
|
C
|
Pena,
Brayan
|
-4
|
+1
|
---
|
-1
|
---
|
1B
|
Fielder,
Prince
|
-6
|
-4
|
-2
|
+1
|
+4
|
2B
|
Infante,
Omar
|
+5
|
+6
|
+10
|
+4
|
+12
|
3B
|
Cabrera,
Miguel
|
-3
|
-4
|
-4
|
-10
|
-18
|
SS
|
Peralta,
Jhonny
|
-11
|
-1
|
+10
|
-6
|
-3
|
CF
|
Jackson,
Austin
|
+8
|
+5
|
+4
|
+9
|
+11
|
RF
|
Hunter, Torii
|
+7
|
+15
|
+10
|
+1
|
+11
|
RF
|
Boesch,
Brennan
|
-9
|
-8
|
-12
|
-5
|
-11
|
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