Most think that Fisher's departure was partly due to his religious and racial comments this past season. (at one point he had up a "praise the Lord" or somethign sign and at another point, after a game, he said he needed to recruit more African Americans, because they were faster.)
But after a remarkable run, he put up three losing seasons and was ousted. Dumb move in my opinion.
By the way, AF lost 13 linemen (OL and DL) this past year due to injury. That's probably why they had a losing season. I was at the UT game and they had a real real chance to win that game but injuries tore through their team the rest of the year.