USC has unresolved issues

USC ends spring practice with its annual Trojan Huddle scrimmage at the Coliseum today at 1 p.m. Five things that are apparent after four weeks of workouts:

Corp-orate feel

Aaron Corp’s running ability will give the Trojans a new weapon at quarterback -- if he can hang onto the job through training camp.

Coach Pete Carroll hasn’t exactly bubbled with enthusiasm since announcing the third-year sophomore as the starter, repeatedly saying that the competition to replace Mark Sanchez would continue.

In the past, that was just Carroll being Carroll. This time, however, he has avoided anointing Corp -- “We had to name somebody and we did,” Carroll said Thursday -- which bodes well for freshman Matt Barkley and, perhaps, junior Mitch Mustain.

Corp seemed to gain confidence almost daily throughout spring workouts, and teammates rave about his emerging leadership ability, improved arm strength and commitment to film study.

But it’s Corp’s backbreaking scrambling ability that really sets him apart.

McNair’s impending nightmare

Managing USC’s stable of tailbacks just got a whole lot tougher for running backs coach Todd McNair.

And he can thank freshman Curtis McNeal, whom Carroll dubbed as the possible MVP of spring practice, and sophomore Marc Tyler.

The two young tailbacks join senior Stafon Johnson and juniors Joe McKnight, C.J. Gable and Allen Bradford in the tailback mix.

Unlike 2007, when that quartet of then-young tailbacks deferred to Chauncey Washington, there is more than one elder statesman around.

They all want carries -- they’ll all be draft-eligible, after all -- and some are not shy about expressing it, sometimes publicly.

Lost and found

Despite losing three potential first-round NFL draft picks, the starting linebacker corps should be strong again in the hands of Chris Galippo, Malcolm Smith and Michael Morgan. But USC would benefit greatly if Luthur Brown could shake injury woes and fill the utility role Thomas Williams filled valuably in 2007.

New assistant head coach Jeremy Bates, who will call plays on offense, could not evaluate McKnight during drills because of residual foot soreness from an injury suffered in the Rose Bowl. Bradford, a star of previous springs, sat out while recovering from hip surgery. And with center Kristofer O’Dowd recovering from shoulder surgery, the Trojans sometimes scrimmaged without snapping the ball.

The 5-foot-8 McNeal is like a new toy for Carroll, and Tyler has lately shown flashes of his pre-broken-leg burst.

Sophomore Armond Armstead successfully transitioned from defensive tackle to starting end and senior Averell Spicer looks as if he will fill the void left by Fili Moala at defensive tackle. Sophomore Tyron Smith emerged as the starting right offensive tackle and sophomore fullback D.J. Shoemate will provide depth behind Stanley Havili.

Walk-on kickers Joe Houston and Jordan Congdon have been dead even, so the Trojans won’t know who will handle what duties until JC transfer Jake Harfman arrives in the fall. Harfman also punts.

Secondary to none

The strength of the defense is perhaps the best secondary of the Carroll era.

Taylor Mays, Josh Pinkard and Will Harris are intimidating safeties, Kevin Thomas and Shareece Wright playmaking cornerbacks.

One of the great treats for fans, if not quarterbacks, will be watching the 6-3, 230-pound Mays approach the line of scrimmage for blitzes.

Sophomore cornerback T.J. Bryant made great strides, while freshman Brian Baucham and sophomore Marshall Jones also performed well.

Forecasting

the future

It’s a tough road schedule with games at Ohio State, Washington, California, Notre Dame, Oregon and Arizona State.

While USC breaks in a new quarterback, its opponents will boast experience at the position, barring injuries.

Ohio State has Terrelle Pryor, Washington Jake Locker, Notre Dame Jimmy Clausen and Oregon Jeremiah Masoli.

USC, however, should be a contender for its eighth consecutive appearance in a Bowl Championship Series bowl game -- and possibly more.

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gary.klein@latimes.com