Recruiting analysts say it's tougher to project which top prospects will succeed in college at quarterback than at any other position.
A look at their rankings bears that out.
Only one of the top nine quarterbacks in the 2013 class started more than three games for the school that originally signed him, according to composite rankings of recruiting websites compiled by 247Sports . That's No. 2 Christian Hackenberg, who played three seasons at Penn State before being drafted in the second round by the New York Jets.
By comparison, nine of the top 15 overall 2013 prospects regardless of position are in the NFL after being drafted in the first two rounds.
''I don't think it's hard to evaluate the physical skills that are required to play the position,'' Alabama coach Nick Saban said. ''But I think some of the most important things in playing quarterback are decision-making, judgment, timing, leadership, accuracy under pressure, and those things are much more difficult to evaluate until a player is actually called upon to do that in your particular system, even in some cases.''
Just four of the top 20 quarterbacks from the 2013 class are currently starting for the schools they originally signed with: Ohio State's J.T. Barrett (No. 10), Tennessee's Joshua Dobbs (No. 13), Stanford's Ryan Burns (No. 15) and North Carolina's Mitch Trubisky (No. 19).
The other four starters from the top 20 are transfers, with only one at a Power Five school. Charlotte's Kevin Olsen (No. 5) originally signed with Miami. Utah's Troy Williams (No. 7) started out at Washington. Northern Iowa's Aaron Bailey (No. 12) transferred from Illinois. Louisiana Lafayette's Anthony Jennings (No. 20) came from LSU.
''It is a tougher position to evaluate,'' said Barton Simmons, the national scouting director for 247Sports. ''There's a litany of factors why, the primary one being that quarterback moreso than any other position is all about intangibles.
''You obviously have to have ability to be successful, but the great ones are the ones that have some things you just can't measure, whether that be toughness or leadership ability or the ability to make plays in big moments and compute all the different things that a quarterback has to absorb over the course of a game, play or season.''
Coaches encounter similar problems trying to decide which quarterbacks to pursue without knowing their mental makeup.
''What you don't see on film is leadership,'' Mississippi State coach Dan Mullen said. ''It's hard to evaluate the processing of information and intelligence because a lot of times you don't know what they're being coached to do (in high school).''
In an era of 7-on-7 tournaments and offseason camps, quarterbacks are seen more often in a variety of different environments before they ever arrive on campus. Simmons believes that generally has made it easier to evaluate but notes analysts occasionally can get ''bamboozled'' by how someone fares in these settings.
Simmons remembers how Michigan's Shane Morris performed so well at 7-on-7 events that it was tempting to overlook his so-so high school completion percentage. Morris, the No. 3 quarterback in the 2013 class, according to the 247Sports Composite, has started only two college games and hasn't thrown a single touchdown pass.
Former NFL quarterback Trent Dilfer says quarterbacks shouldn't be judged solely on how they perform in those types of controlled environments. Dilfer works as a head coach of Elite 11, a quarterback competition for prospects across the country.
''The analogy I give all the time is what if the PGA Tour went and gave you a card based on how you hit it on the driving range?'' Dilfer asked. ''It would be such a different PGA Tour. The guys that actually get the ball in the hole and know how to compete and how to overcome swing flaws and bad days and wind gusts and bad lies and all the other things that come with it, they're the guys who win.''
Mike Farrell, the national recruiting analyst for Rivals, says 7-on-7 events and camps can measure a quarterback's physical traits. High school results can show how he performs in game situations. But there's still a key element missing.
''The one thing you can't replicate when you're scouting a high school quarterback is a 280-pound future first-round defensive end coming around the edge in his face,'' Farrell said. ''What is he going to do then?''
It isn't just the high bust rate of top prospects that reveals the difficulty of projecting which quarterbacks will succeed in college. There also are the quarterbacks who outperform their rankings. Consider the case of Louisville sophomore Lamar Jackson, the early Heisman Trophy front-runner who was rated a three-star prospect (on a scale of five) by multiple recruiting services.
Farrell, whose service rated Jackson as a four-star prospect, understands why the former Boynton Beach High School star has exceeded expectations.
''We didn't know that running away from everybody in South Florida would translate to running away from everybody in the entire country in college,'' Farrell said. ''He looked fast, but he didn't look this fast.''
Jackson also found the right spot at Louisville playing for Bobby Petrino, and perhaps that's the biggest key to projecting success.
Dilfer isn't convinced that it's more difficult to evaluate quarterback prospects, noting highly regarded recruits at other positions also often fail to live up to their rankings. But he does believe that finding the right school is more important than having the most talent.
''Do you fit where you're going?'' Dilfer said. ''Do you fit athletically? Do you fit in terms of your ability to actually (play) quarterback? Do you fit into the style of play they use? Do you fit into the culture? Do you fit into the school? Do you fit into the social environment?
''It's all about fit.''
AP Sports Writers David Brandt and John Zenor contributed to this report.
Online: The AP's college football page: http://collegfootball.ap.org