You've probably noticed when you sim the starters all play 40+ minutes (most of the time).
I think I figured out why, you can try it out and see if it works for you.
When you lower player's fatigue ratings to 10 and less, you'll see a better distribution of minutes.
Some players like Kobe, Lebron, etc. do play a lot of minutes, I have their fatigues at 15, other starters and other players who play a lot at 10, and anyone else at 5 or even 1.
I sim a league with Live so I don't actually play games, so I had to figure out a way for our stats to come out more realistic.
I think primacy will keep the total number of shots down too, even when guys play 40 mins, they don't always take 20-25 shots, so perhaps having your better players start out at lower primacies, let's say 40-50, and everyone else below that, you'll see your better players taking less overall shots, that I have not tested yet, but its worth a try.
Maybe there's another fix to this issue and I simply didn't find it, if that's the case please let me know.
Please keep in mind I'm talking about simming games, not playing them and the computer never subs, which we all know is a well documented bug.