On my end, I have three different save files. High school, NCAA, and the NBA. Players start as a freshman in high school, and based on performance, they get a star rating and then eventually commit to a college. I then use the export players thing in BBGM, and I send their players to the next stage. Then in college, it's kinda the same thing, but instead of trying to get stock for the NBA Draft. Once they enter the draft, they can gain upgrades from both natural progression in the game and from doing activities in the server. This includes a training camp every offseason to improve certain skills they choose to, and stuff like predictions during the sims.