Extra observations from Sunday's scrimmage, plus surplus notes, quotes and video:

• The Trojans are lacking in depth at a number of positions across the field -- which makes the quarterback spot particularly interesting. Yes, as we detailed yesterday, the third-string spot will be filled by either a walk-on or a true freshman, but the top two players at the position are arguably among the top five or so in the nation. Backup Mitch Mustain, playing against mostly second-stringers, had a terrific scrimmage on Sunday, showing his worth and even out-performing Matt Barkley. But there is no semblance of a quarterback controversy in the land of Troy, not with Lane Kiffin dismissing that question Sunday and again calling Barkley his starter. One benefit from Mustain's success in the spring and fall: according to Kiffin, the coaching staff can use the same game plan for both signal-callers and will not have to develop a second plan for each game as a contingency plan.

• Nickell Robey, 18, stands at just 5-foot-8 and 165 pounds but displays an alarming willingness to challenge players who have six or more inches and 50 or more pounds on him. The scrappy Florida product made four tackles during Sunday's scrimmage, including one bone-crunching hit on running back Marc Tyler that came behind the line. Robey has undoubtedly been the most impressive of the three freshmen corners -- Anthony Brown and Demetrius Wright are the others -- and could see playing time in nickel or dime situations if his solid performances continue. The 19-year-old Brown remains a likely redshirt candidate.

• Players are starting to get used to the long hours of fall camp. The schedules so far have been very demanding, with players up by 6:30 a.m. and in nearly non-stop football activities until bed checks at 10:30 p.m. Those 16-hour days leave very little time for anything else, although the schedule will be a lot less arduous when classes start Aug. 23.

• Tight end Jordan Cameron was just about the unquestioned star of the scrimmage, with eight receptions for 96 yards -- including a 39-yard gainer. Sunday was probably Cameron's best scrimmage to date, including the spring, and it marked a striking rise to importance for Cameron. An impressive athlete, the 22-year-old went to BYU out of high school to play basketball but could not break into the rotation as a first-year freshman. From there, he transferred to Ventura J.C. for the 2007 season, during which he caught 22 passes as a tight end (!) and earned all-conference honorable mention. He came to USC for the 2008 season and playing sparingly as a receiver, spent the winter months on the basketball team while appearing in three games but not scoring a point and again played marginal time at receiver in 2009. More on Cameron's journey below.

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Cameron has made a lot of changes over the past four months.

In April, I asked him what he did well as a tight end. "I don't know what I do good," he said at the time. "I'm just learning the position right now. I would say I'm a pretty good route runner, being a converted receiver, so I think I can run the routes they need me to run." And blocking-wise, how could he improve? "Just working on the technique during the summertime -- obviously gaining weight and getting physical -- but technique and footwork and hand placement are all key to blocking."

Here's some of what Cameron had to say Sunday. Notice the difference in his confidence level?

It's not only Cameron and his coach who have increased confidence in the tight end's game. It's his quarterback, too. Sophomore Matt Barkley talked after Sunday's practice about the development of several of the skill-position players on offense, including Cameron: