Progression is pretty good IMO, depending on the players' potentials, some players will develop into stars, role players, and busts as well. But it's realistic cuz 1st rounders can be busts, and if you scout out a really good 2nd rounder with good potential, they can become somewhat productive as well.
And from my experience in free agency, how good your team is also plays a big part. If your team sucks, or a player is unhappy, they'll decide to test free agency instead of simply resigning with you. And I've had a bunch of cases where players accepted an offer with less money to play on a winning team.
And draftees have pretty realistic stats, but sometimes I'll see players on the all rookie 2nd team averaging 2 pts/2 rebs a game. It's not a big issue tho, and overall, association is by far the best and most fun part of the game.
Hope that helps.