Spring depth chart: Defensive line

There are three Mondays left until spring practice officially kicks off for USC on March 22. On each of those Mondays, we'll preview one-sixth of the Trojans' depth chart and eye potential risers and fallers during the monthlong springtime. We began three weeks ago with quarterbacks and running backs and continued two weeks ago with receivers and tight ends and last week with offensive linemen. This week, defensive linemen, keeping in mind that Ed Orgeron's group tends to move around a lot, so we put players at multiple positions:

Defensive end

1. Armond Armstead, senior

2. Wes Horton, redshirt junior

3. Kevin Greene, redshirt sophomore

4. DeVante Wilson, freshman (won't enroll until fall)

Assuming Armstead is available in the spring, he's the surefire starter at this end spot, a senior with the size, build and experience for the position. He's not a world-beater as a pass-rusher, but he does enough in those situations to make himself a threat and is really one of the best run-stopping ends in the country. Horton is of starting caliber but is the third-best end on this squad, so look for the USC coaching staff to give him plenty of snaps both in spring practice and during the season.

Greene is a linebacker-turned-defensive end who is still quite inexperienced at the position and needs more seasoning before he can be counted on to play serious snaps. Wilson will likely redshirt.

Under tackle

1. DaJohn Harris, redshirt senior

2. George Uko, redshirt freshman

3. Christian Heyward, freshman (won't enroll until fall)

Harris is the glue guy that will keep this line together, a solid but mostly unspectacular player who really shined in spring practice last year and kept that going for most of the 2010 season. He lost his nose-guard job for a few games last season when the coaches decided to move under tackle Jurrell Casey to nose and Armstead from end to under tackle but regained it later in the year. He's never been in tip-top physical shape at USC, so that will be something to pay attention to.

Uko could have easily played last fall, members of the coaching staff admitted, but was redshirted instead as a way to combat sanctions and conserve resources. He's made a lot of physical improvements over the past few months, you can tell from winter workouts, and he could easily finagle his way into the line rotation this upcoming season.

Heyward's a nice prospect who's a very smart player but will need to redshirt to develop more physically.

Nose guard

1. Christian Tupou, redshirt senior

2. George Uko, redshirt freshman

3. Antwaun Woods, freshman (won't enroll until fall)

Tupou missed all of the 2010 season when he tore a knee ligament in the spring game last April, but he was on the sidelines for every practice and game throughout the year and will likely not miss a beat upon his return in the spring. He's not the most physically gifted player, at 6-2 and 290 pounds, but he's already started 23 games for the Trojans over the last three years and doesn't miss very many tackles.

Uko will be almost interchangeable between the two tackle spots this year, but he'll probably be more of an under tackle in the future. Woods will likely redshirt but stands a small chance to play this fall if USC needs the depth available.

Defensive end

1. Nick Perry, redshirt junior

2. Wes Horton, redshirt junior

3. Greg Townsend Jr., freshman (won't enroll until fall)

Perry is the only true pass rusher on this defensive line, as the other starters are more run-focused players. Because of that, he'll probably again play more snaps than would be ideal -- Lane Kiffin said last year he was over-playing him -- and could push for 10 sacks on the year. Horton's going to play both end spots.

Townsend Jr. is probably the least likely of the four defensive line recruits to redshirt, because he's (1) fairly physically developed for his age and (2) an exciting pass rusher, even at this stage in his career.

That's it for today, but keep in mind that other players could find their way onto this depth chart before the spring is over, including tight end Christian Thomas, who played some end last year, Steve Dillon, a 2011 recruit who has yet to officially sign his letter of intent and James Boyd, a two-year player for the Trojans who is not on the spring roster at the moment but could be back on it at some point. We'll be back next week with a look at the linebackers and defensive backs.