Lots of reasons probably. Some that come to mind.....
-Different expectations...I think the Cats were highly ranked preseason in 04.
-I think people underestimate having consistent on-the-field leadership under center. In 04 and 05 they cycled too many QB's in and out with thin skill sets. Low reps per QB led to: inconsistency, confidence problems, game plan issues, etc... I don't think KSU really put a team together this year until they decided to really stick with GG.
-Some of KSU's defensive match ups in conference play this year have been built to stop spreads and heavy passing offenses of the past few years. Snyder talked a little bit about exploiting this in preseason interviews.
-Maybe the team just got tired of people thinking they weren't good players and some fundamentals helped more than most would have thought. (should revisit some old threads regarding coaching vs. talent arguments).
