Five things we learned in the spring, No. 4

USC’s spring practice is done and football is officially over until the first week of August, so we’re going over the five biggest things we learned this spring.

We went over De’Von Flournoy‘s surprise spring Monday, defensive back depth on Tuesday and offensive tackle struggles on Wednesday. Our fourth thing is this: The USC Trojans defense is being built to better stop the spread.

They are subtle switches, but they're switches all the same.

Monte Kiffin is slowly but surely molding his USC defense into a more spread-friendly unit, we saw this spring. Essentially, the Trojans are adjusting to the rest of the Pac-12 in emphasizing speed more than ever, and it makes sense.

Evidence: All the experiments USC conducted this spring were tilted in one direction: Seeing if smaller players will fit at bigger positions, like trying safety Tony Burnett on the strong side of the linebacking corps and trying defensive end Greg Townsend Jr. on the inside of the defensive line.

We saw some of this last year, too. Based on the perspective the Trojans demonstrated in Lane Kiffin's first season at the helm of the program in 2010, they never would have tried out safety Dion Bailey at linebacker. But that spring experiment worked out well, and it worked even better in the fall when USC realized they could keep Bailey and fellow outside linebacker Hayes Pullard on the field in second- and third-down situations and not get completely exposed.

A lot of the struggles the Trojans had in 2010 were related to that. They used Devon Kennard as a middle linebacker, not his natural defensive-end slot, and they weren't quick enough to defend Oregon for four full quarters. Heck, they arguably weren't even quick enough to stop Arizona.

But they were last season. And they should be again in 2012, with basically every player across the entire defense on the smaller size, weight-wise. Wes Horton and George Uko might be the only USC defenders with prototypical frames for their positions.

Another potential get-small move for the future is putting incoming freshman Leonard Williams at defensive tackle. He's a nice-sized defensive end, but he could be a workable three-technique tackle, which is one of the Trojans' biggest needs behind Uko.

The Kiffins have demonstrated creativity with assembling their defense of late, and there's no reason to think they won't continue to this fall and beyond.

Check back Friday for our final thing we learned this spring.