We ranked Oregon Ducks quarterback Marcus Mariota the No. 1 prospect for the 2015 NFL draft after studying tape of him and the rest of the top prospects this offseason. His upside is huge, given his mix of physical talent, mental makeup and intangibles, but there are also aspects of his game that NFL decision-makers will want to see him improve this season. He gets an early opportunity to show off his improvement Saturday against a Michigan State defense that in many ways resembles the unit from Stanford that has been his and the No. 3 Ducks' kryptonite the past couple of seasons.