While Mariota has largely been the favorite all season long, not to mention my preseason pick, I think it is easy to forget that Mariota seemed to be on pace to win the award a year ago before struggling (by his standards) down the stretch following a loss to Stanford in early November, clearing the way for Jameis Winston to take the award with ease. But considering how spectacular Mariota has been (an insane 38-2 touchdown-interception ratio plus 14 rushing touchdowns), there is no question that Mariota is a well-deserved winner of the award.
But how about the other finalists, Wisconsin running back Melvin Gordon and Alabama wideout Amari Cooper? Both had tremendous season by every logic (Gordon with an incredible 2336 rushing yards on 7.6 yards per carry plus 26 touchdowns; Cooper with 115 receptions and 1656 receiving yards, both of which lead the country), and may indeed have the "Heisman moment" that Mariota may lack. However, Gordon was hurt by a lackluster performance against Ohio State in the Badgers' embarrassing 59-0 loss while Cooper may have been held back by his position as there has not been a Heisman winner to play receiver since the great Desmond Howard in 1991 (and only three overall, if you count Johnny Rodgers as a receiver).
But all in all, Mariota deserves the Heisman and he is expected to win it by a significant margin tonight. His future seems relatively promising I would say with his Ducks playing in the College Football Playoff semifinal in the Rose Bowl and New Year's Day as well as him considered to be the favorite to be the first overall selection in the NFL Draft come April.