Edit rookie stats before drafting?

Is this possible? E.g. If i'm in 07-08 season, can I edit generated rookies' ratings before I draft them for 08-09 season?

You can do it, but I'm not sure if it's safe from crashes. Just remember the name of a rookie you want to edit and find him in players.dbf file. Once he's generated, he will be there.

Before editing that, make a backup.

Not all stats are filled up.. I've tried editing plyrvalue. Will that have effect?

It should, because as far as I can remember there is no overall rating for generating rookies till the draft is finished. So the game probably counts it from that plyrvalue.

The overall is calculated from the individual stats though so you might find it's recalculated again after a player is drafted.