To address the whole playing up, playing down debate:
As a high school coach:
1. You don't want to lose players ever.
2. You don't want to lose a player in a game against an inferior opponent as much as you don't want to lose a player against a superior opponent.
3. More than anything else, you don't want to lose a player in a game that doesn't count. Conference games carry more weight than non conference games.
I don't think it changes much at the college level. A lot of programs are not so deep to handle the loss of a star playing like McGhee. Regardless of whatever coaches may or may not being saying, this would be Ash's worst nightmare. Losing your quarterback, your heart and soul of your program, is not quantifiable. Prukop and Bleskin are talented QB's, they should be or they wouldn't be there, but you aren't just replacing statistics.
Now, MSU is behind the 8 ball, because regardless of what quarterback takes the helm, Bleskin or Prukop, is going to have one heck of a steep learning curve over the next weeks. Heck either of those guys might be the second coming of McGhee and MSU may never miss his statistical presence. I would measure a guess is that MSU is going to struggle, because few players can step on the field in the college game as a quarterback and not experience the difficulties of playing that position.
The season's outcome, albeit a bit mature, may be cast for MSU by a last ditch hope to win a game that didn't matter. I am not criticizing Ash cause I would have done the same, to try to seal a victory but at the same time one cannot begin to fathom the enormity of that attempt on MSU's fate as well as the rest of the BSC's fate for the remainder of the season.
Best of luck the McGhee in his rehab. I do hope he returns healthy as soon as he can.