If you are referring to Miles's time here, I'd put it on a combination of recruiting and scheme.

Les seems to embrace a pro-style approach, as compared to a spread or an option-run based offense. Came in and had Jamarcus 2 years, and allowed him to do enough to merit being the #1 pick in the draft. Ran a lot of 3 WR sets with him. Flynn followed and had a nice season (and we won the BCS).

Next season was supposed to finally be the Perilloux era, but that never happened. Unfortunately for us, it was tough to recruit a QB when you have a star in waiting, so suddenly we were stuck with scrubs and freshmen. Don't forget, in 2008 we started Hatch ahead of Lee, because Lee just totally didn't get the offense; and Hatch probably couldn't throw the ball 40 yds in the air. When Hatch got killed against Auburn, Les tried Lee until he set all sorts of pick 6 records, and then pulled the redshirt off Jefferson to finish the season.
We then couldn't find a QB to beat these guys out. Maybe the QB crops were weak, as Shepherd was supposed to be the top dual threat in the nation, and he never saw a snap at QB.
Recruiting- they aimed at Zach Lee, who went to MLB instead. They aimed at Gunner Kiel, who crawfished out of here, Indiana, Notre Dame, and landed at Cincy (it's interesting to note that his brother was a QB at Indiana but also left the team; maybe Les' "lack the chest" comments are a family issue).

Landed Mettenberger, who after sitting a year, started his junior year and looked lost a lot (you actually had time to say "good God, throw the ball away" out loud before he'd get sacked), before becoming great his senior year.
We now have Harris. As crazy as it sounds, Harris seemed to have more presence as a soph than Mett did as a junior. He COULD take the next step in his development next year.