Nick Marshall is known for a two-year career as Auburn's quarterback that included an SEC championship and a trip to the 2014 BCS title game. His signature play, a 73-yard, deflected, last-minute touchdown pass against Georgia, dubbed the "Prayer in Jordan-Hare," sparked that surprising run.

Now, after throwing for more than 4,500 yards and rushing for almost 2,000 more at Auburn, Marshall is embarking on a journey as unlikely as that play.

Nick Marshall, Auburn's quarterback the past two seasons, lined up at cornerback in the Senior Bowl. He hopes to make it in the NFL as a defensive player. Stacy Revere/Getty Images

He's trying to make the switch from college quarterback to NFL cornerback.

College quarterbacks have tried for years, with mixed results, to transition to other positions as a way to have a better chance at NFL success. Michigan's Devin Gardner, who is making the move to wide receiver, is joining Marshall on that path in this year's draft class.

Doug Graber, Marshall's positional coach at the EXOS training facility in Gulf Breeze, Florida, and a former NFL defensive coordinator, has worked with NFL prospects for 13 years. He came away impressed after Marshall's first workout as a defensive back before the Senior Bowl in January.

"I've never had a kid like this that's converted this late," Graber said. "This was a unique experience for me, too. That's why it was so surprising the very first day I worked with him."

In Marshall's initial workout, Graber saw sharp cuts, a fluid backpedal and athleticism. He saw enough basic fundamental successes to believe the switch could work. It solidified Marshall's decision -- which was made after a conversation with his mother -- to abandon quarterbacking and head down a risky path.

Patriots receiver Julian Edelman and former Steelers receiver Antwaan Randle El are among the few college quarterbacks who have thrived in the NFL at other positions, but the transition typically produces limited success.

Most college quarterbacks who change roles, like Gardner, look to become wide receivers. Some, like Jacksonville's Denard Robinson, end up as running backs.

Patriots receiver Julian Edelman put his QB experience to use against the Ravens in the playoffs. Jared Wickerham/Getty Images

The shift Marshall is making to defense is exceedingly rare. Former Nebraska quarterback Scott Frost became an NFL safety and enjoyed a 59-game career, mostly on special teams.

With Graber's endorsement, Marshall played cornerback at the Senior Bowl, and his performance confirmed Graber's initial reaction and intrigued NFL evaluators.

"He played corner and ran with [Phillip Dorsett] from Miami," said St. Louis Rams general manager Les Snead. "The kid from Miami made him hedge, but Nick was step for step. What that did show you is he's either just as fast as this kid from Miami, or he's got some football instincts that let him know how to play some coverage and know that, all right, that guy's fast, I need to do this and this and this angle to make sure I stay with him."

Invited to the NFL scouting combine as a quarterback, Marshall ran a 4.54-second 40-yard dash and now is a viable cornerback prospect. NFL teams appear to be intrigued in Marshall as a quarterback, as well. Despite saying he is committed to being a defensive back, he threw at the combine and Auburn's pro day at the request of scouts.

There's a reason it's rare for a college quarterback to successfully change positions. It's a rapid learning process that must be executed during the biggest job interview of your life while competing against some of the best athletes in the world.

For Marshall and Gardner, however, it's not a completely foreign concept. Gardner played a half season of wide receiver at Michigan, and Marshall initially went to Georgia as a defensive back before switching to quarterback at Garden City Community College in Kansas and continuing at Auburn.

Former Michigan quarterback Devin Gardner played receiver for half of the 2012 season, catching 16 passes. AP Photo/Tony Ding

"The most difficult part is the backpedaling, getting my legs in shape by backpedaling," Marshall said at the combine. "Then technique-wise things and recognizing the receiver routes and the route combinations that are going to be thrown at me."

Imagine having to learn another language in four months and speak it fluently in order to secure your dream job. It's a challenge for both the players and the scouts evaluating them.

"Any time you're looking at guys making a position change, you're betting on a lot of the unknowns," said San Francisco 49ers general manager Trent Baalke. "You're looking at traits, makeup, trying to decide whether the traits of that player, the makeup that that player has fits into the role that you see him moving into."

Gardner caught two passes during the East-West Shrine Game in St. Petersburg, Florida. Kim Klement/USA TODAY Sports

Every decision-maker has a different process. Pete Carroll digs deep when evaluating players like Marshall and Gardner. The Seattle Seahawks coach knows that video and the usual evidence used for making projections won't be there.

"You do a lot of homework," Carroll said. "Find out what position he played in Little League. All that."

Seriously?

"Heck yeah," Carroll said. "You find out as much as you can to figure it out, and then you take a shot. You just take a shot in the dark, and see if it works."

It's an interesting approach. But in a league where bad drafts lead to unemployment for coaches and general managers, "a shot in the dark" can be dangerous.

Once Carroll does his research -- Marshall and Gardner, for instance, were skilled basketball players in high school -- he looks for athletes with a "general sense and knack" for football. Those players adapt faster.

NFL evaluators want to see speed, athleticism and a commitment to the new position. Even with all the boxes checked, it's a difficult undertaking. Marshall is rated as the No. 33 cornerback by ESPN, and Gardner is the No. 57 receiver.

"It probably took me four to five months to understand it's going to be a while," said Marques Hagans, who converted from quarterback at Virginia to receiver and played in six games during an NFL career that lasted two seasons (2007-08). "It set in at six months that this is a longer process than I really thought it would be."

Marshall performed cornerback drills during Auburn's pro day, but scouts also wanted to see him throw. AP Photo/Butch Dill

Many players who have made the conversion said teams were patient with them. Typically, if a franchise is interested, there is going to be extra scouting involved.

"You pull clips from the video to put a tape together of what the player might bring to the table," said ESPN analyst and former Cleveland Browns general manager Phil Savage, who signed three-time Pro Bowl kick returner Josh Cribbs as an undrafted quarterback out of Kent State. "Then as far as an extra workout, it would be a one-day situation. A one-day deal where you would visit him at the school and visit coaches again and make sure the player is embracing the idea.

"Then you want to put him through some of your own drills, just to convince yourself he can do it."

Savage said he would watch film on all the interceptions Marshall threw at Auburn. He'd watch post-pick pursuit. Were there good instincts? Did he take a good route to the ball carrier? If he made a hit, what did it look like?

There might only be a handful of these plays -- Marshall threw 13 interceptions in two seasons at Auburn and 20 in one year at Garden City -- but they can give front offices something to work with.

Scott Frost moved to safety in the NFL after playing quarterback at Nebraska, a rare transition from signal-caller to defense. Al Bello /Allsport

Savage said he also would watch tape of Marshall at Georgia. It's more than three years old, but it can offer clues. The Georgia tape leads at least one NFL general manager to think Marshall can make the move.

"It's not a Scott Frost situation, where Scott went to Nebraska as a quarterback and was a quarterback," Snead said. "This kid went to Georgia as a DB, and then he moved to quarterback."

Savage said prior to the combine he could see Marshall as a mid-round pick, something he considered remarkable given how long it had been since he regularly played defense.

With Gardner, the projection is a little easier. There is film of him playing receiver, along with quarterback scrambles on broken plays from his Michigan career. It gives an idea of his elusiveness and decision-making.

It's all still a guess, though.

"It's obviously a huge projection, you know," said Detroit Lions general manager Martin Mayhew. "You can get burned making projections, projecting guys to do things that you don't get an opportunity to see them do. Devin played some receiver in the East-West game, so we had an opportunity to review that tape and see him do it and watch him practice at receiver.

"So you have kind of a feel for what kind of player he would be. But like Denard Robinson moving to running back, those are all projections; and I think he's done well in Jacksonville. But you have to be careful in those situations."

Pittsburgh Steelers general manager Kevin Colbert met Randle El at the 2002 combine. Colbert saw athleticism from Randle El's time as Indiana's option quarterback. At the Senior Bowl, Colbert watched Randle El catch punts and play receiver. Then came Randle El's combine interview.

By meeting's end, Colbert was intrigued by the quarterback turned receiver. He loved Randle El's personality and skills, and the Steelers had worked with multiposition players before in Kordell Stewart and Hines Ward.

Antwaan Randle El completed 22 of 27 passes with six touchdowns during his NFL career. Allen Kee/NFLPhotoLibrary

"You want to have as much predictability as possible, and when you're converting somebody, there's always an element of unpredictability," Colbert said. "It's uncomfortable, but sooner or later you have to make that decision.

"Fortunately for us and Antwaan, it worked out."

The Steelers drafted Randle El in the second round, and he provided immediate value as a returner. Contributing on special teams is usually a key element for quarterbacks trying to make a switch. Cribbs' primary role was as a special teamer. Robinson, a former Michigan quarterback, embraced special teams while he learned to play running back.

Marshall displayed his punt return skills at his pro day. It's unknown how Gardner might fare on special teams, since he never did so at Michigan and his pro day was not open to the public.

Former Michigan quarterback Denard Robinson led the Jaguars with 582 rushing yards in 2014. John Grieshop/Getty Images

Randle El said it took him half a season to understand Pittsburgh's playbook to where he asked questions for confirmation instead of lack of understanding. Despite his quarterbacking background, it took him a full season to learn disguised coverages. He caught 47 passes as a rookie and had a nine-year career as a productive receiver and returner.

What helped Randle El in addition to his athleticism, coaching and having strong mentors in Ward and veteran receiver Terance Mathis was that he could play in the slot. That's another wrinkle for making the transition. Many make the move because they aren't tall enough to play quarterback in the NFL, so becoming a slot receiver makes sense.

While Randle El believes he could have succeeded as a pure outside receiver, playing slot made it easier.

"If you're inside, you've got so much room to go outside, so much room to go inside, so much more room to play with," Randle El said. "If you're on the outside, the sideline's not your friend from that standpoint, so you have a smaller space you have to work in.

"When you're the slot guy, I could start on the left side of the field and end up on the right side of the field. I could start on the left side of the field and end up on the right tackle side, come back the other way, catch the ball and go 60. It's more just playing tag, if you will, from that standpoint."

This, Randle El said, could be an issue for Gardner: Unlike many of the other converted quarterbacks, he is 6-foot-3½ and 218 pounds -- built like an outside receiver.

When you ask Gardner why he'll succeed where so many others have failed, his answer is simple.

"I'm a competitor," he said. "I'm good at playing football. I've been good at playing football my whole life. The first day I ever played receiver in college, I won my first, second and third one-on-one."

But history says there will be almost certainly be challenges he doesn't anticipate.

Pre-existing injuries slowed him when he started training as a receiver. He had success with in-based routes but struggled on out-breaking routes, which isn't uncommon for taller receivers.

Bill Cunerty, Gardner's trainer at EXOS, is confident his client can succeed as a receiver, but he'll admit he doesn't know for sure. Gardner ran a 4.62-second 40-yard dash at Michigan's pro day; 32 receivers posted faster times at the combine.

While training at EXOS, Gardner ran routes by himself, not against press coverage with a physical cornerback bumping him off stride. When Gardner enters a team's camp, he'll have to adjust to that. His routes can be precise against invisible defenders. In games, it will be something entirely different.

"You have to understand how to give a guy a dead leg if you're running sideline routes," Cunerty said. "I'm looking at Julian Edelman, who was a quarterback, and Julian Edelman as a receiver is quite a dramatic product, because he took his knowledge as a quarterback and how to run routes and matched that to the speed and the timing of the throw."

Cunerty and Gardner have worked on this. Gardner also reached out to Edelman, who is the best current barometer for NFL success in the transition after a 105-catch year in 2013 and 92 receptions last season.

One piece of advice from Edelman stuck out the most.

"Take care of your feet," Gardner said. "In camp, your feet are going to get real beat up, so take care of your feet."

It's true. Gardner will likely run more in one week of practice at receiver than he might have in an entire season as Michigan's quarterback.

Add the sharp cuts needed to run precise routes, and it can wear down an athlete.

It's no surprise, however. When making this move, everything is a transition.