Something I've never seen discussed, but something I have always taken to be true based on my observations. SIM AI teams will always start players locked to position, but then the SIM will fill the rest of the depth chart according to their rating of ability.
i.e. SIM has three good upperclassmen Cs and two terrible frosh PFs, the SIM will by default start one of the upperclassmen at C and one of the freshmen at PF. Then the other two upperclassmen, by virtue of being "better", will fill as the two backups at C and PF.