We are starting a series today taking a look at what several Pac-12 teams must do to catch reigning Pac-12 champion Stanford. First up: USC.

How they make the Pac-12 championship game: After appearing in their first Pac-12 title game in 2015, the Trojans will enter next season expecting to make a return trip to Levi's Stadium in early December. With the effects of the NCAA sanctions playing less of a role in how the roster is constructed, USC now has a nice mix of youth and experience for new head coach Clay Helton. Assuming Helton doesn't have any significant first-year hiccups, it's not difficult to envision a rematch against Stanford. The Trojans have an All-American-caliber receiver in JuJu Smith-Schuster, a budding superstar in running back Ronald Jones II and several other capable skill guys that will benefit from what should be one of the conference's top offensive lines. They have to replace starting quarterback Cody Kessler, but the primary candidates to replace him -- Max Browne and Sam Darnold -- are both talented players who would be expected to play at a high level almost immediately. Defensively, Adoree' Jackson and Iman Marshall form one of the nation's top corner tandems for new (old) defensive coordinator Clancy Pendergast, who is widely expected to be an improvement over Justin Wilcox.

What's holding them back: They're really thin on the defensive line -- at least in terms of experienced players -- and that could potentially serve as a fatal flaw. It's an area that has been addressed through recruiting in each of the last two classes, but until these younger players prove then can get after the passer and disrupt the run, there will be questions. The same can be said about Helton, a first-year head coach (officially), and Tee Martin, a first-year offensive coordinator. It's hard to really gauge what kind of impacts the coaching changes will make until the actual season begins. And even then, starting the year against Alabama and then opening the Pac-12 schedule two weeks later at Stanford doesn't exactly allow for an easing-in period.

X factor: Will the distractions go away? Two high-profile in-season coaching changes in three years, plus a litany of other off-the-field issues have made for a bizarre stretch for the USC program. The players have become seemingly desensitized to it all, but if they can finally just focus on football the results should improve.