You're under the spotlight at all times, and there are entire message boards dedicated to what you're doing right or wrong. I really appreciated the linked post, and feel really bad for the guy, but that's what college football is. One regular complaint against Sitake is that he doesn't make these sorts of tough decisions often enough, that he lets coaches and players continue when they're not getting the job done.
In short, he can't simultaneously be loyal to those who are loyal to him, and also dedicate himself to the single-minded pursuit of victories. This season was a disaster, and while Clark may not be at fault any more than anyone else, not making changes would have done more harm than standing by every last member of the team and staff.