South Florida's defense was one of the 20 best in the country when it comes to preventing big plays on standard downs, and one of the 20 worst when it comes to preventing big plays on passing downs. If you can figure out how that happens, let me know, because I'm somewhat at a loss.
Below is a list of the 25 teams with the biggest differences in defensive performance on standard and passing downs. Evidently this phenomenon can mean one of two things. If you are a young team (and therefore return quite a few starters the next year), then this could be a sign that you have some misplaced, youthful aggression issues that are likely to improve the next year. The average improvement for all teams with a) at least a 20-spot difference between Standard Downs S&P+ and Passing Downs S&P+ and b) at least six starters returning the next year is higher than the average improvement of teams based solely on returning starters. Meanwhile, the regression for teams returning five or fewer starters is stronger too. So basically, this Standard Downs > Passing Downs phenomenon is a multiplier of sorts. It probably means good things for a USF team that returns six starters, but we'll see.
I've had close, personal experience with a couple of the teams on this list. The 2009 Missouri defense was absolutely loaded with freshmen and sophomores, which made their passing downs breakdowns both predictable and explainable. With a good pass rush and an experienced secondary in 2010, Mizzou flipped things around quite well. USF wasn't quite as young as 2009 Mizzou, but quite a few redshirt freshmen did seem to make an impact.
Def. F/+ Chg
|2010 South Florida||18||107||-89||20||105||-85||6|
|2010 Kansas State||69||119||-50||59||120||-61||6|
|2007 Air Force||53||109||-56||49||110||-61||+8.1||5|
|2008 New Mexico||8||76||-68||12||70||-58||-15.1||3|
|2007 Boston College||23||70||-47||24||78||-54||+5.6||4|
|2007 Wake Forest||22||83||-61||21||74||-53||+5.8||9|
|2010 Fresno State||62||94||-32||40||92||-52||5|
|2010 Oklahoma State||16||68||-52||18||70||-52||5|
|2006 Michigan State||62||99||-37||47||97||-50||+3.2||6|
|2008 Arizona State||12||42||-30||11||60||-49||+3.3||6|
|2008 Southern Miss||37||101||-64||52||100||-48||-4.1||9|
|2009 San Diego State||76||111||-35||65||111||-46||+5.0||7|