I'll answer - it's because all offenses in the league are worse. In conference games, we've gone from 10th last year to 9th this year in YPP.
There may be some truth to this. At the same time, I think there are a few other factors at play. For one, I think our improved running offense has greatly benefited our D. I don't care to do the research, but I have watched every game this season and I am quite confident that 2009 time of posession is greatly improved over 2008. Thus, there should be a direct negative correlation to the number of offensive possessions our opponents have had in 2009. Our greatly reduced number of turnovers and increased number of forced turnovers have also kept our D off the field.
Coaching is clearly another factor. Prince tried to replicate the quick-fix spread offense. He knew our JuCo Defensive Coordinator couldn't gameplan for sh1t and that the only way to compete was to score a lot of points. Unfortunately, our passing game was simply subpar. "3-and-out" was a common theme last year. And by the 4th Q, Wyatt would be talking about how gassed the D looked.
Long story short, several reasons the D is playing better this year.