I thought that this was a known fact. I cant recall where I read/heard this, but I've been operating under the impression that aggression drops when players get into early foul trouble, leading to fewer fouls, but less effective defense as well. I don't have any proof, other than anecdotal evidence of players getting four fouls in the first half, and not fouling out until 40 or so minutes in.
I may have been mistaken in saying that players in foul trouble back off.
Nope, this part I'm certain is true, and recall direct affirmation od this from a BB or two, though, like those posting above me, I can't recall where. I have a problem with this statement:
But I stand by the fact that let them play is better
Which I believe is not true at all, but go on,
because even if thats not true, instances of foul outs in 30 minutes or less are far more rare than instances where a player with early fouls sits for far too long using sit them.
I'd be happy to see this tested with two teams full of aggressive players pitted against each other, one playing "sit them," the other playing "let them play," and note which team gets more reliable minutes (to starters and trainees, I'd assime), as this seems to be your concern as I read your posts.
My experience of having a team that is traditionally filled with players who are more, often than not, aggressive (4/7 of my currnet competitive team is so inclined), I've found "sit them" to be exceptionally more useful than "let them play." This is particularly true when lined up against opposing players who are also aggressive, and whose owners have "let them play." While I don't have time to find a decent number of examples games as proof, here's a game that immediately sprung to mind
(8412013) (If you have time to watch it, pay special attention to the PF position.)