Five things we learned in the spring, No. 2

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, avoiding basic topics like who surprised and who disappointed in favor of broader, longer-term issues.

We went over De'Von Flournoy's surprise spring yesterday. Today, our second thing is this: This team's defensive back depth might actually be one of its biggest strengths, contrary to what recent history would have you believe.

Here's a good example of how the USC secondary is so much deeper this year than it has been in any recent season.

The coaches used to have to switch trackster Tony Burnett back and forth from corner to safety during his first two seasons with the program to add temporary depth wherever it was lacking. This spring, there was so much depth there that they moved Burnett to an entirely new position: strongside linebacker, where he looked to be thriving in the final week.

That's the kind of luxury all this depth is going to give new defensive backs coach Marvin Sanders and the Kiffins in 2012.

All the starters return at corner and safety, and then four or five more potential starters also return or enter in behind them, depending on how you look at it. There is simply a ton of depth across the board, so much so that an incoming signee like Kevon Seymour might be forced to redshirt as a freshman because of a sheer lack of available snaps.

Last year, it wouldn't have been farfetched to expect Seymour to come in and start right away.

What will USC be able to do because of that extra depth? Well, it's going to make redshirts more likely for Seymour and fellow incoming freshman Devian Shelton. But it may also allow newcomers Josh Shaw and Gerald Bowman to learn the system without a rush to get on the field in camp.

For Bowman, in particular, that could be a key benefit. He has difference-making potential, but it would've been a lot easier for him to fulfill that potential if he enrolled in the spring. It also means Burnett's probably going to stay at linebacker for his final season. Even if he struggles some there, it just makes more sense from a get-on-the-field perspective.

Considering the other units across the board, the only other ones that come close to the overall depth of the defensive backs are the quarterbacks and the tight ends -- with experience still an issue under center and health a serious issue at tight end.

So, yes, things have changed in the USC secondary.

Check back Wednesday for the second thing we learned in the spring, involving USC's offensive tackles and something they still need to work on.