It costs a lot to switch coaches. Not only do you lose recruits that they've worked to develop and hopefully sign, but you also lose development time by switching, and sometimes you take someone out of the running entirely by switching schemes from different extremes.
We've had the worst of all worlds with our switches.
Power-I-Option to West Coast Offense to continued WCO for a year and then to spread, then to Pro Offense, then back to another kind of spread.
More depth, more talent, more time, more consistency
Not to mention a switch to the B1G.