Osborne was announced as the AD on 10/16/07, three days after the OSU loss. We then lost to A&M, Texas and Kansas, the KU loss being the 76-point game. Immediately after we lost to KU we pummeled KSU and scored 70-something points doing it, then lost to Colorado the next week, giving up another 65 points.
I know people think that Callahan could have kept his job had he only won those games, but I just do not see it. Osborne was brought in to return Nebraska to its roots, and Callahan was NOT the guy to do that. In fact, he was about the polar opposite of that.
Even if we'd have beaten Texas and made the other three losses after TO took over respectable, the odds of Callahan keeping his job the way he helped ostracize past Huskers and the way he so eagerly changed the culture of the program, there's no way he would have stayed.