I stand corrected. Customer service told me it was impossible to stay at A+ in D3 after losing in the first round when I filed a ticket when I clearly had the best four year run of any team in D3 Phelan by a good margin but there were a dozen teams ahead of me in prestige.
I can't figure why this won't let me post a table but the link is
http://www.whatifsports.com/hd/TeamProfile/History.aspx?tid=14588 and the drop in prestige was after season 15.