I play by LLM rules...
if a player appears in my game through scouting, media reports or assistant/coach recommendation then I'll look at them, similarly if he plays against my team or I happen to see him in a game I've gone to watch (e.g. reserves/youth next opponent, etc)
if they don't then, as far as I'm concerned, they don't exist... even though I may know about them in RL or because I've seen them mentioned in a forum post or whatever.
I don't even sign players I might have signed in previous saves, never mind previous versions, unless they show up by one of the above routes...
realism FTW!