that is rather strange. im not sure the 4 season window logic applies though, that was just for jobs, i think. if alblack is right about prestige going all the way back, the only question you'd ask is, was the current season a b- season or better?
did the prestige possible drop when you got there, or possibly go up when broncosboy got there? when coaches come, they impact the existing prestige... if thats not the answer, that would imply your season was considered worse than his, which i struggle to believe, my perception of prestige includes a decent weight on record, especially at lower prestiges. but maybe at the higher prestiges its rpi, or maybe even position on the projection report, which would be pretty cool (albeit unlikely).