I put everything in words. Assists+plus plays-negative plays-errors divided by innings played for IF. Putouts+assists+plus plays-negative plays-errors divided by innings played for OF.
IOW, Greg Woods makes 3.19 plays "good isolated solo plays" per 9 while Hector Arias makes 0.70 per nine. They're credited for good plays and deducted for bad ones. That way, your C playing 1B with 19 negative plays is credited appropriately. I'd say, on my MG team, that Woods' defense is worth more than 4 times as much as Arias'.
Really, I use it to compare players on my team but it works in determining who's defense is "more important" and by roughly how much.
My other 1B:
Eduardo Oliva
|
1B
|
1.232000
|
Hector Arias
|
1B
|
0.077844
|
Felix Cashman
|
1B
|
0.047619
|
Vic Mercado
|
1B
|
0.030534
|
Mercado is a butcher.