Oregon's biggest challenge in 2015

Even with the loss to Ohio State in the College Football Playoff National Championship presented by AT&T, the Oregon Ducks can lay claim to being a perennial powerhouse. The Ducks have posted 10 or more wins in seven straight seasons, and coach Mark Helfrich's 24-4 record is the best start by a Pac-12 coach in more than 60 years.

As impressive as those achievements are, this program still has to win a national title before it can truly take its place as an elite program.

Losing quarterback Marcus Mariota to the NFL draft will make it harder to reach that goal, but the reality is that Mariota's departure is far from the biggest hurdle the Ducks will face in 2015. Without some significant defensive improvements, this team will be hard pressed to repeat as Pac-12 champion.

Offensive talent won't be an issue

Replacing Mariota, who was arguably the best quarterback in college football history, won't be easy, but the Ducks have a ton of talented players ready to step up.