I always wondered what the ratings are based on because if you compare some players then some ratings just don't make much sense. I always edit the ratings myself and it's pretty much based on "Ron Shandler's Baseball Forecaster". It's a good book to use for ratings (and for fantasy baseball, of course
) because of the stats they use and stuff like PX and SX so it's not too much work for me. My ratings are usually based on the last 2 seasons and the results were pretty good in the past.
Of course some things are weird sometimes if you edit stuff yourself because u can't edit managers and their decisions, playing time/platoons, how often players have green light and stuff so the right ratings sometimes have a wrong outcome what makes things really hard. Just an example: Stephen Drew is at least as fast as Carl Crawford (that's a fact btw) but he doesn't even steal more bases than Albert Pujols. How u wanna edit that? It's impossible. So u have to edit Drew that he is a) way to slow in the game or b) he steals way to many bags. So NOW it's pretty much impossible to edit the players the way that it results in let's say 90% plausible stats. You just can rate the players' skills perfectly but you can't influence how the game's using each player. I'd say NBA 2K11 is the only game were u can edit stuff the way that it is really close to real life.