How Accurate are the Ratings for different leagues?

[wbcfan]

I was wondering if anyone knew how accuarate the ratings were for the different leagues.
For example, I used former journeyman minor leaguer Sharlon Schoop as an example and looked at what his overall rating would be in different leagues world wide on the 20-80 scale.
In
MLB he was a 20
AAA=30
***=35
KBO=35
AA=40
CPBL=40
A+=55
A= 65
A-=80
(R)(Pio/App/GCL/DSL=80
Jpn AA=50
Kor (F)=65
Cuba=45
Mex=40
CPBL (2)=65
ABL=50
Dutch=50
Italy=50
German=55
France=60
Czech=55
Spain=55
Atlantic League- 45
Am Association= 50
Can/Am=50
Frontier=55
BCL=55
Pac Association= 60
PECOS=70
Japan Indy- 55

Sorry for the lengthy post, but where I have a problem with the ratings is in the lower level minor leagues. He's a 65 in A ball, an 80 in A- and Rookie ball, but only a 50-55 in the European pro leagues,)which is a lower level of play than all affiliated ball. I'm not trying to sound like a jerk, just looking for a bit of insight. Thanks!