Fall Camp Storylines: Who Has Barkley's Back?

With fall camp slated to begin Monday, we'll be examining a few lingering storylines the Trojans must sort out as they begin preparations for the upcoming 2012 season. In part four of five, we look at the left tackle position.

USC returns nearly its entire offensive unit that put up point after point after point (all 429 of them) last season. But there will be one giant piece missing when the Trojans open fall camp Monday.

Matt Kalil skipped his senior season, entering the NFL Draft where he became the fourth Trojan tackle in the last five years to be selected in the first two rounds. Kalil was selected No. 3 overall by the Minnesota, giving USC back-to-back top 10 offensive tackles after Tyron Smith was the No. 9 pick by Dallas in 2011.

The Trojans return the four other starting offensive lineman, but someone has to have star quarterback Matt Barkley's back. Who will be asked to replace the 6-foot-7, 295 pound Kalil and continue USC's new offensive tackle tradition?

The leading candidates are redshirt junior Kevin Graf and sophomore Aundrey Walker -- two mammoth men in their own regards. In spring practice, Graf started at left tackle the first week, but Walker took over for the final three weeks.

Graf has the experience and the bloodlines. Like Kalil, Graf's older brother paved the way previously playing on the offensive line at USC. But Graf's father, Allan, also wore the cardinal and gold in the trenches and has a 1962 national championship to show for it.

Last fall when Kevin Graf entered camp, the coaching staff wasn't sure what they had. He had played only sparingly in 2010 after redshirting as a freshman. Graf was also coming off shoulder surgery that had forced him to miss 2011 spring practice.

But Graf was a solid cog in the offensive line, anchoring the right side of the line. With his pedigree and 6-foot-6, 290-pound frame, Graf is fully capable of switching to the left side and taking over as Barkley's backside protector.

The frontrunner after spring practice was Walker, however. Graf may have proven his abilities last season, but the coaching staff loves Walker's length and prototypical left tackle size. He is currently listed at 6-foot-6, 300 pounds but he entered USC weighing around 375 pounds. He played at 320 pounds in the spring and slimmed all the way to 296 in the offseason, according to ESPN Los Angeles' Pedro Moura.

Walker told our Joey Kaufman in the spring that he was "gasping for air" after four plays in a row last season before his weight loss. He'll need to be able to bolster his conditioning and use his quick feet to contend with the speed rushers of the Pac-12.

It is also still a learning experience for Walker. Coming out of high school, he was ranked by rivals as the No. 1 guard recruit in the nation. Walker primarily played right guard for Glenville High in Cleveland, Ohio. When he was took over as the starting left tackle in the second week of spring practice, it was the first time he had played left tackle full-time in his high school or college career.

Barring injury, don't expect to see any of the freshman battle Graf or Walker for either of the tackle positions. After 2012, expect to see Zach Banner pushing for playing time. The son of a former NFL lineman, Banner, has the size to be a future NFL tackle -- potentially continuing the offensive tackle tradition after Graf and Walker.

If Walker doesn’t take command of the position early in camp, it will be interesting to see how this battle progresses. Would the coaching staff leave Graf at right tackle where they are comfortable with his production from last year and go with some form of rotation with Walker, Banner, and/or Nathan Guertler and David Garness, who are currently listed as the backup tackles?