A random thought crossed my mind today while looking at some of my minor league teams.  What would happen if everyone in my world demoted their entire ML rosters to Low A ball.  Would the season progress exactly the same?  The point of the question I guess is what determines the level of play?  Is it the level of the league or the opponents you're facing? Clearly if I was the only one to demote my entire ML roster to Low A ball, I would clean house.  (Well, not by that much, considering how ****** my ML team is right now... hence the thought experiment...)

But does the level of play depend on what level the player is placed in?  I'd imagine batter/pitcher battles would be pretty much a function of player match-up ratings.  But what about fielding?  If the entire ML was demoted to LowA would errors pretty much be non-existent? It seems to me that at ML SS would make much fewer errors if in LoA.  Is it because its ML hitters hitting it harder?  Or does the sim engine just assign glove ratings to different levels as they'll make X% of the plays hit to them.

No.  Send a stud ML hitter to LoA against LoA competiton and he destroys it.   Send a ML hitter to face ML hitting and he hits like you'd expect.  It's about the ratings of the players he's facing. 

Right, what about the fielding though?  Does the game factor in who's hitting the ball?   More + plays for the ML SS down in LoA?

No.  Ratings are ratings.  Level of play would not factor into it.  Why would you think otherwise?

This isn't even hard to check for yourself.  Look at your minor league leaders.   The SS with 7 errors in AA will have comparable ratings to the BL SS with 7 errors.