Im not a big computer/sim guy. i play these games totally based on my knowledge of the actual players that i remeber. But I was wondering is there any home park advantage for players who played in certain parks during their careers? will Billy Williams perform better if hes playing in Wrigley ? will Ron Guidry pitch better at Yankee Stadium?  can the sim detrmine these things?

(A) you're asking these questions in the wrong forum. Use the Sim League Baseball forum for questions about the sim works.
(B) No, there is no special effect based on whether a player actually played in any give park.

The sim is a very simple game, based on a very simple statistical model.