Ok, Knowles is gone.  Everyone will be processing that over the next few days and I'm sure this forum will discuss every possible reason, possibility, and replacement ad nausum. 

I have a different question.  Is the 4-2-5 defense still the answer in the first place?  Let's face it, the tide of college football has been moving away from the spread/tempo offenses for years.  Michigan "won" technically (let's not get distracted here) by putting three tight ends in and marching the ball down the field with some intermediate passing and the occasional play action tossed in.  Notre Dame does the same, as does Ohio State, PSU, UGA, and Texas. You are seeing this all over the place, teams are moving back to the hog packages with ball control and clock-killing schemes.  I can't think of a single Power 5 pure "spread" team.

Knowles's defense (4-2-5 with the Jack position) was designed to defend the spread with, to be fair, lesser talent.  His defense was designed around subterfuge as much as anything.  It was a way for Oklahoma State to compete in the Big 12 during the no-defense era with 2-3 stars.  It was a QB confuser defenses.  Is it still what we want in the first place?

I felt that our defensive issues four to five years ago were as much of an issue with not having a real defensive coordinator and taking a flyer on Combs because we didn't want to change at that point in the recruiting cycle.  Day was scared of being burned deep and that became the focus.  Whatever it takes, don't let us get hurt deep.  That was an admirable goal but was it an issue because of Combs?  Maybe Combs was just THAT bad.

We lost the first Oregon game this year and struggled with some other important teams when we could not get off the field on third and 3rd and 3.  We also seemed to have trouble getting pressure on the QB when needed.  After the Oregon game, we seemed to play a much simpler base defense that resembled the 4-3.  The results were pretty good.  We stopped the run and we were getting increased pressure.

I guess the question is, is it time to change the thinking a bit?  Do we go back to a system where we take our ability to recruit great players and put them in positions to make plays instead of trying to confuse the other offense as much pre-snap with bizarre blitzes and linemen dropping into coverage?  Nothing we did in that National Championship run was exotic.  We were just in the position to make plays.