The difficulty in forecasting the Heisman Trophy field increased well before Johnny Manziel broke through the redshirt freshman ceiling and Jameis Winston followed him.
Since Sam Bradford's win in 2008, few have had the eventual winner on their preseason radar, and no summer favorite has actually hoisted the trophy since Matt Leinart in '04.
While unexpected contenders are certain to rise, each conference looks to have defined candidates as we close in on the season.
Here is a look at the top challengers from each of the Power 5 leagues and the rest of the college football:
1. Jameis Winston, QB Florida State, RS Soph.: The fourth Heisman winner coming off a national title (joining Doc Blanchard, Matt Leinart and Mark Ingram), Winston will -- fair or not -- face an entirely new set of expectations this season. In the last six attempts at trophy No. 2, no one has finished higher than third.
2. Duke Johnson, RB Miami, Jr.: He fell 80 yards short of 1,000 in a sophomore year cut seven games short by injury and was 53 shy in '12. With the Hurricanes breaking in a new QB, he should get plenty of chances and while health is a concern, so is a South region that includes both Georgia's Todd Gurley and Alabama's T.J. Yeldon.
3. Karlos Williams, RB Florida State, Sr.: The year after Leinart took home the trophy in '04, his teammate Reggie Bush stole the Heisman spotlight. Williams, who had 730 rushing yards as a backup despite never getting more than 13 carries in a game, will take the lead role and could see a rise in admirers considering the microscope the Seminoles will be under.
4. Vic Beasley, DE Clemson, Sr.: Every summer we Heisman pundits throw out a number of defenders who will ultimately never truly factor in -- remember, no strictly defensive player has ever won and only Manti Teo has come close in the last 33 years -- and Beasley, who was third in the nation in sacks last year with 13, will be among those getting that buzz this time around.
5. DeVante Parker, WR Louisville, Sr.: He racked up 855 yards and 12 touchdowns as a junior, despite missing one game and getting two or less receptions in three others. But he's going to have a new QB in Will Gardner and is playing a position that last won in 1991 with Desmond Howard.
1. Braxton Miller, QB Ohio State, Sr.: After missing nearly three games last season, the biggest concern with the Buckeyes passer and last year's preseason favorite is his health. With Carlos Hyde and Kenny Guiton no longer in Columbus, he's a strong bet to make New York if he can stay on the field.
2. Melvin Gordon, RB Wisconsin, RS Jr.: No James White, who had more carries than Gordon last year, should result in an uptick for the senior as he takes the lead with Corey Clement behind him. After averaging 7.8 and 10.0 yards the previous two seasons, respectively, he could be a lock for 1,700-plus yards.
3. Ameer Abdullah, RB Nebraska, Sr.: The Cornhuskers have never had a player post three 1,000-yard rushing seasons. Abdullah could be the first. He is working behind an offensive line that returns just one starter, but last year's line was injury-ravaged and he still managed to rack up 1,690 yards.
4. Jeremy Langford, RB Michigan State, Sr.: His string of eight straight 100-yard games last year was a school record and he returns bigger, bulking up to 210 for his senior season. Word is the Spartans will lessen Langford's workload between the tackles and will work to get him the ball in space out of the backfield.
5. Christian Hackenberg, QB Penn State, Soph.: When it comes to NFL-prototype QBs, there may not be a better one in college. Hackenberg threw for 2,955 yards and 20 TDs as a true freshman, and while he'll miss WR Allen Robinson and has a rebuilt offensive line in front of him, he looks poised to become a household name.
Baylor's Bryce Petty threw for 4,200 yards and 32 touchdowns last season.
1. Bryce Petty, QB Baylor, RS Sr.: Petty missed the ceremony last year despite throwing for 4,200 yards and 32 touchdowns to just three picks. He put off the NFL to return and has six of his top seven pass-catchers from a year ago at his disposal. With a manageable schedule through October, he figures to be in the race for the long haul.
2. Trevor Knight, QB Oklahoma, RS Soph.: Was the 348-yard, four-TD Sugar Bowl performance against Alabama a sign of things to come? He struggled with accuracy last season and appeared in three games in which he started and wasn't removed because of injury or play. But he's caused a furor with his potential on a team that should be a playoff threat.
3. Malcolm Brown, RB Texas, Sr.: The Longhorns last had a 1,000-yard rusher with Jamaal Charles in 2007, and Brown was 96 yards short despite not getting more than nine carries until Week 6. Considering the Longhorns QB situation, Charlie Strong will likely ride the ground game, giving Brown a stage to live up to that five-star rating he arrived with.
4. Tyler Lockett, WR Kansas State, Sr.: He's neck and neck with Baylor's Antwan Goodley in the Big 12 receiver pecking order, but while Goodley has to share a stage with a big-name QB, Lockett doesn't. He's also among the country's most explosive players, averaging 17.3 yards every time he touched the ball in '13.
5. Davis Webb, QB Texas Tech, Soph.: He had a strong spring, showing further development on the heels of leading the Red Raiders to an upset win over Arizona State in the Holiday Bowl (403 yards and four TDs). If his postseason outing was any indication, he should put up huge numbers in his first full season at the helm.
1. Marcus Mariota, QB Oregon, RS Sr.: The favorite to dethrone Winston, Mariota is the classic candidate: he'll have big numbers, be in the thick of the national title race and is a household name as the star of a marquee program. He was in this role last year and couldn't deliver, meaning he should have no lack of motivation this time around.
2. Brett Hundley, QB UCLA, RS Jr.: Hundley has some big early games to make an impression, including against Texas on Sept. 13, vs. Pac-12 South champ Arizona State on Sept. 25, and an Oct. 11 meeting with Mariota in the Rose Bowl. But consistency is key for Hundley after three games with 66.7 or worse completion rates in his last four outings.
3. Taylor Kelly, QB Arizona State, RS Sr.: The last two seasons he's passed for a combined 57 TDs and 6,674 yards, but Kelly has largely flown under the radar. His interception total -- 21 the past two years, including 12 in 2013 -- and completion percentage (62.4) last fall are concerns, but he's increased his yards and touchdowns each season as a starter.
4. Myles Jack, RB/LB UCLA , Soph.: If a defender is going to win, a la Charles Woodson in 1997, they are going to have to have some offensive touches sprinkled in. Jack fits that mold, running for seven TDs and averaged 7.0 yards per carry. His biggest problem is a better candidate on his own team in Hundley.
5. Ty Montgomery, WR Stanford, Sr.: An All-American last season who anked second in FBS in kickoff return yards (30.3 per), Montgomery also averaged 157.7 yards of offense a game (ninth). He's simply dynamic, scoring receiving, rushing and return TDs a year ago and benefits in the passing game from working with veteran QB Kevin Hogan.
1. Todd Gurley, RB Georgia, Jr.: With Aaron Murray off to the NFL, Gurley figures to be the focal point of the Bulldogs offense. He's mentioned a run at 2,000 yards, which would surely get him to New York, but health remains a concern as he missed three games last year, finishing 11 yards shy of 1,000. In a deep class of SEC backs, he leads the way.
2. T.J. Yeldon, RB Alabama, Jr.: Like Gurley, he'll be working with a new QB, meaning Nick Saban could be looking at his RBs to shoulder more of a load. As strong as Yeldon has been (2,343 yards and 26 TDs over the past two seasons), he's certain to have plenty of competition for touches in his own backfield with the likes of Derrick Henry and Kenyan Drake.
3. Nick Marshall, QB Auburn, Sr.: After helping the Tigers to the final BCS title game, he enters the year as the face of the SEC at QB. Gus Malzahn is expected to put more of an emphasis on the passing game in Year 2 for Marshall, and coupled with a 1,000-yard rushing season, he could put up some trophy-worthy stats.
4. Mike Davis, RB South Carolina, Jr.: He's overshadowed by Gurley and Yeldon, but Davis had seven 100-yard games last season, which was one more than Yeldon and three more than Gurley. With the Gamecocks starting a new, but experienced QB, and down their top receiver, defensive game plans will center on stopping Davis.
5. Dak Prescott, QB Mississippi State, RS Jr.: Prescott threw for 1,940 yards and ran for 829 more last season and totaled 23 TDs. He's the SEC's active leader in rushing scores by a QB (17), but was erratic at times in his first year as a starter, throwing seven picks and completing 58.4 percent of his attempts.
Navy's Keenan Reynolds set a single-season record for touchdowns by a quarterback with 31 in 2013.
1. Everett Golson, QB Notre Dame, Sr.: Back for the Fighting Irish after a semester-long academic suspension, Golson spent his exile from the program working with noted quarterback guru George Whitfield Jr. If it all leads to a leap up from his first-year stats (58.8 completion rate and six TDs), he could play his way into the mix.
2. Keenan Reynolds, QB Navy, Sr.: His 31 rushing TDs last season was a record for a QB and he ran for 1,346 yards to go with 1,057 passing. It's tough getting attention at a service academy, having not produced a top-10 vote-getter since Air Force's Beau Morgan in 1996, but Reynolds has a chance to make an immediate statement Aug. 30 vs. Ohio State.
3. Rakeem Cato, QB Marshall, Sr.: A non-Power 5 player last won the award in 1990 with Ty Detmer, but Cato has a statistical nugget to push, as he has thrown at least one TD pass in 32 straight games, six off Russell Wilson's record. With a easy schedule, he should put up big numbers and keep himself and the Thundering Herd on the national radar.
4. Chuckie Keeton, QB Utah State, RS Sr.: Keeton's junior season was cut short by a torn ACL injury and after gaining a medical hardship waiver, he returns looking to build off 2012 when he was 17th nationally in total offense (307.1 ypg). He'll have a chance to answer any questions about his knee early as the Aggies open at Tennessee.
5. Taysom Hill, QB BYU, Jr.: Eighth in FBS in total offense last season -- he passed for 2,938 yards and ran for 1,344 -- which put him ahead of the eventual Heisman winner, Winston. The Cougars' schedule has enough key games (Sept. 6 at Texas; Oct. 3 vs. Keeton and Utah State, Oct. 24 at Boise State) to make voters pay attention.
