Brian Anderson's Defense

I know it's still somewhat small sample sizes but Harball Times has out Win Shares.  I noticed Brian Anderson's fielding win shares were right up at the top of the list.  I also looked up Range Factor and Zone Rating on ESPN.  It's very impressive.  If he can just get his avg up to .250 and continue to take walks like he is, I will be overjoyed.  Currently his OBP is 100 points higher than his avg.  

Range Factor: 3.56 (1st in AL/1st in all of ML CF's)
Zone Rating: .892 (6th in AL/10th in all of ML CF's)
Fielding Win Shares:1.6 (2nd in AL/5th in all of ML Outfielders)

I'm not a complete expert, but if you have less range isn't it easier to have a higher zone rating?  For example, Vernon Wells has a .933 zone rating, but his range factor is only 1.99.