That, as we noted on Tuesday, makes Oregon the 2014 Pac-12 favorite, no matter that running back De'Anthony Thomas and/or cornerback Ifo Ekpre-Olomu are unlikely to follow his example. In fact, the Ducks are a good bet to begin the season with another top-five ranking, in large part due to Mariota still being behind center -- his two-time first-team All-Pac-12 center Hroniss Grasu, no less.
Marcus Mariota's return should leave the rest of the Pac-12 chasing Oregon in 2014.
If you include RB Byron Marshall over DAT, the Ducks will surround Mariota with nine other returning starters -- the only senior on their most recent depth chart was receiver Josh Huff. On defense, things are more iffy, with just five starters back, though a lot of the backups saw plenty of action this past season.
Every other conference team that has reasonable designs on contending next fall will have more questions than Oregon.
Arizona State and Stanford, who play Saturday for the right to go to the Rose Bowl, are senior-heavy teams. Both will welcome back their quarterbacks, Taylor Kelly and Kevin Hogan, respectively, but they will take significant hits on both sides of the ball, particularly on defense. UCLA also is likely welcoming back quarterback Brett Hundley, and it looks like the South Division favorite, but it, too, will be replacing some key star power on defense, starting with outside linebacker Anthony Barr.
The most preseason buzz, however, will surround Oregon, and Mariota will be the guy on the cover of all the magazines.
While Ducks fans aren't really looking ahead just yet because many are crossing their fingers over an outside shot at a BCS bowl game -- Discover Orange Bowl vs. Alabama! -- there is enough of a pause in the action to consider the state of the Ducks.
Was Year One under Mark Helfrich a success? A failure? Somewhere in between?
Some Ducks fans, the national-title-or-bust ones, already view it as a failure. Others would join that crowd if Oregon loses its bowl game, wherever that may be.
The more reasoned position is to be mildly disappointed that it became a transitional year, post-Chip Kelly, and that specific circumstances -- Mariota's sprained knee and a uniquely deep Pac-12 -- waylaid what was clearly a pretty darn good team, perhaps as good as any of the other Ducks BCS bowl teams.
As you might have noticed, it's not easy to go undefeated. Just ask Baylor, Alabama and every other college football team unfortunate enough not to play Ohio State's, Florida State's and Northern Illinois's soft schedules. Kelly, as big as his brain is, managed only to do it once before losing the national title game. That year, however, the only other Pac-12 team that ended up ranked was Stanford, and the third-best record in the conference was 8-5 USC.
In other words -- and most Pac-12 fans should not read the end of this sentence -- 10-2 isn't that bad. Notice that no other conference team did better.
But who said rationality was part of being a college football fan?
So, knowing that irrational impatience typically prevails, Helfrich is fortunate to have Mariota returning. A third-year starter at quarterback will provide stability and leadership. It's no guarantee of success -- see USC's Matt Barkley -- but it solves the most critical position on any football team. The 2014 team will start with a 10-win over-under.
Of course, Ducks fans will embrace the over. That's life in Eugene now. Helfrich is well aware that he took over a program that no longer sees eight or nine wins as a successful season. He could be 21-4 at the end of the next regular season, but if the Ducks aren't headed to the inaugural College Football Playoff, there will be a strong sentiment that the program has taken a step back under Helfrich.
Mariota is the biggest reason to bet the over. He's the biggest reason Helfrich might coax some breathing room out of his second go-around.
Still, one of the big stories in the Pac-12 in 2014 will be which way the Ducks trend: Do they regain their footing atop the conference? Or does evidence accumulate suggesting a clear decline?