At any given time, there are typically only eight to 12 people who are qualified to be NFL starting quarterbacks. Worse, it’s not always clear who those players will be, as veterans age into decline and big-ticket free agents go bust with new teams. It’s no surprise, then, that raw and untested quarterback prospects — whose pro careers are projected based on college game film, combine measurements, a few interviews, and some throws made indoors against air instead of a defense — fail more often than they succeed.

Unless an NFL team has a historically great defense, however, it’s nearly impossible to win a Super Bowl without a top-tier signal-caller, which means general managers and head coaches must grit their teeth and draft quarterbacks. And they must draft them high.

Enter this year’s top three quarterback prospects: Central Florida’s Blake Bortles, Louisville’s Teddy Bridgewater, and Texas A&M’s Johnny Manziel. All three of these quarterbacks are underclassmen who declared early, won lots of games while posting big numbers in college, and possess many of the key skills talent evaluators prize. All three also have glaring flaws that must be addressed, which means none of them is a lock for NFL success.

That, however, is precisely what makes this draft so fascinating: Bortles, Bridgewater, and Manziel are all first-round talents with fifth-round flaws, and which of them a given personnel man or fan likes best says as much about that person as it does about that quarterback. They’re different players, but they’re united by the uncertainty that surrounds them. Each QB is a Rorschach test for the evaluator, which makes examining these three prospects in turn a way to study the larger, gut-wrenching process of evaluating and drafting players who can make or break careers.

Click here to read all of Grantland’s 2014 NFL draft coverage.

The Talent: Blake Bortles

While bigger college programs recruited Bortles to play tight end, Central Florida coach George O’Leary saw a talented 6-foot-5 quarterback he thought he could mold into a top-flight operator for his offensive attack, a pro-style/spread offense mash-up. It worked, as Bortles rewarded O’Leary’s faith with a 12-1 record and a Fiesta Bowl victory last season. Now, Bortles needs NFL talent evaluators to take the same chance O’Leary did.

There’s no mistaking Bortles’s natural ability, but there’s also no mistaking his need for additional polish. There are times he still looks like a tight end playing quarterback, a long-lost Gronkowski brother trying to read defenses and throw touch passes. Bortles’s tight end qualities aren’t all bad, however, as he’s fearless, is an excellent athlete, and is the only top-three quarterback prospect with a prototypical NFL body. When he puts his entire frame into a pass, Bortles can deliver a strike.

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Far too often, though, Bortles’s throwing motion looks plain weird. Like a golf swing or a jump shot, a quarterback’s throwing motion should be a single, fluid movement. Bortles, however, often steps without transferring his weight, or transfers his weight but only afterward pulls his throwing arm through. These issues surface most frequently when Bortles is facing pressure, because although he’s naturally poised, his mechanics are unrefined and thus break down when he’s under duress. Against South Carolina’s constant pressure, for example, Bortles delivered a flurry of off-target throws.

Some evaluators have dismissed these concerns as a “footwork issue” that NFL coaching will remedy, but I’m not so sure. Bortles’s upper body presents just as many issues as his lower body, and getting all his movements in sync will be no small task. The team that drafts Bortles will likely need to rebuild his entire throwing motion. Bortles delivered some beautiful passes in college, but the NFL is about consistency, and he’ll struggle finding that until his mechanics improve.

The good news is that it’s a lot easier to improve the mechanics of a superior athlete than a plodder. And despite his size and prototypical “drop-back” quarterback label, Bortles’s real strength in college was throwing rhythm passes underneath and while on the run. He was effective on read-option plays and fantastic at roll-out and sprint-out passing, including his game-winning pass to knock off then-undefeated Louisville and catapult UCF to a BCS bowl last season. He was also great on screen passes, as he displayed a knack for drawing in and manipulating defenders while finding creative ways to get the ball to his backs, including the talented Storm Johnson. That’s a more difficult skill than many realize, and it further highlights Bortles’s athleticism.

Right now, though, I’m less worried about Bortles’s flaws than about what teams see when they look at him. I see a big, athletic quarterback with a great feel for operating out of the shotgun and throwing on the move. I also see a prospect who has the talent to develop into a good downfield passer capable of making complex reads, though he was rarely asked to do so at UCF. Many NFL general managers, however, see something very different: old-school NFL. As former Chicago Bears GM Jerry Angelo wrote for the Sideline View: “The reason I like Bortles best is because he’s the prototype of what successful NFL quarterbacks historically look like.”

In short, they see tradition. But while Bortles may look like a “traditional” quarterback when he’s in a T-shirt and shorts at a workout, he doesn’t play a traditional game. If teams have Bortles atop their draft boards because of how he looks rather than how he plays, they’re going to be disappointed. “When [Bortles, Bridgewater, and Manziel] walk into a room, one looks like a quarterback,” CBS reported one team GM saying. “The other two? Not so much.”

Unfortunately, “looks like a quarterback” too often means big, tall, and white. What’s more, it’s not a very effective way to select a signal caller. For every Troy Aikman, there’s at least one Jim Druckenmiller, and no quarterback looked the part more than recently failed first-rounder Blaine Gabbert, who earned the Remember the Titans–inspired nickname “Sunshine” on the pre-draft circuit then provided little of it as a pro.

Just because some NFL evaluators are wrong about Bortles’s style doesn’t mean they’re wrong about his promise, of course. While I have him behind both Bridgewater and Manziel on my draft board, he has more upside than either. Like his fellow top prospects, Bortles can be vexing. But if he can consistently play like he did against Penn State last fall, and if he lands with a team that embraces him for what he is instead of what it thinks he should be, he can become an NFL star.

The Technician: Teddy Bridgewater

Former 49ers coach Bill Walsh knew a thing or two about quarterbacks. “You can see if [a quarterback prospect] locates that secondary receiver — or maybe even an emergency outlet receiver — with ease or with a sense of urgency,” Walsh wrote. “This should work like a natural progression, not a situation where it’s — ‘Oh, my gosh, now I must look over here … no, over there.’ You can see which quarterbacks handle these situations with grace. These are the types who have a chance to perform with consistency in the NFL.”

No draft prospect handles these situations with more grace than Bridgewater. At Louisville, Bridgewater was in total control of the Cardinals’ complex offense, the most classically “pro-style” attack any big-time 2014 prospect ran. He checked pass protections at the line, adjusted routes and run plays, looked off defenders, and read defenses; his mastery of and comfort in that system led many to predict last fall he’d be the no. 1 overall pick come May.

That doesn’t seem very likely now. Bridgewater, who was bound to be dinged for his 6-2 height and visibly slight frame, saw his stock plummet following a less-than-stellar pro day. Bridgewater, who always wore a glove at Louisville, decided not to wear one at his pro day, and analysts used words like “average,” “confused,” and “disaster” to describe the results.

Bridgewater’s pro day could have and should have been better, as he missed a few throws and wobbled some others. Still, it’s foolish to try to glean too much about any prospect’s NFL future from how well he performs in shorts while throwing 65 passes to receivers who aren’t facing defenders. Judge for yourself.

One pro day shouldn’t undo three years of excellent film. For example, Bridgewater delivered the single best college throw of any quarterback who will be drafted this year or was drafted last year. Following the 2012 season, Bridgewater entered the Sugar Bowl against a fifth-ranked Florida defense that fielded as many as eight future draft picks. After Jon Bostic blasted him with as violent a hit as you’ll ever see, Bridgewater responded with this beauty:

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Scouts and analysts become enamored of long bombs and so-called “flash plays,” but it doesn’t get any better than this throw, which only a special quarterback could make. Despite his pass protection breaking down and an unblocked rusher instantly appearing in his face, Bridgewater delivered a strike. While the laser throw was impressive, the more amazing thing is how he managed it: Bridgewater calmly identified the coverage and the defenders he wanted to target (the middle linebacker and the nickelback defending the slot receiver) with a high/low pass combination, then used his eyes to hold the backside safety, who was rotating down in a “robber” coverage and trying to read Bridgewater so that he could break on any inside throw; Bridgewater looked off the safety to his left before calmly and fluidly finding a window and delivering the ball to his receiver in stride.

Bridgewater may not have a rocket arm, but he’s more than capable of making NFL throws, as this play indicates. Arm strength is important, but it’s also frequently misunderstood. The key is whether a quarterback can make NFL throws, like deep out-routes to the wide side of the field. It doesn’t matter if a kid can throw the ball 80 yards from his knees if he lacks accuracy or timing.

Teams know this, but knowledge doesn’t lead to better draft results. While most franchises build their draft boards in a similar way, assigning grades so that they can compare players across positions, the process remains more art than science. This is particularly true for quarterbacks, who deliver as much value from the neck up as the neck down.

Bridgewater in particular has suffered from this fluid, undefined process. A year ago, he looked like he’d be the consensus top pick in 2014, but as the months leading up to the draft turned to weeks and the weeks turned to days, second-guessing set in, and it became tempting to focus on measurable traits like height, weight, and the ability to throw a ball 75 yards at the expense of other factors that matter more. It happens every year, and it’s how guys like JaMarcus Russell and Gabbert shoot up teams’ boards.

Based on purely objective criteria, Bridgewater is probably not a first-rounder. Any team that’s watched him play, however, will know that his understanding of the game, accuracy under severe pressure, and toughness are what make him special. That Sugar Bowl berth? Louisville earned it only after Bridgewater came off the bench to beat Rutgers despite a broken left wrist and sprained right ankle.

Given the nature of the NFL draft, I’m not surprised Bridgewater has gotten knocked around late in the process. I also won’t be surprised when he’s an NFL success.

The Playmaker: Johnny Manziel

Do yourself a favor: Watch Johnny Manziel. Don’t watch a cynical draftnik attempt to project whether Manziel’s talents will “translate to the next level” — we’ll get to all that soon enough. Just take a moment to be a football fan and watch him play. It doesn’t matter where you start. You can watch every touchdown from his Heisman-winning 2012 season, or maybe the cut-ups of his 562-yard performance against Alabama from 2013. His bowl performance against Duke last season is as good a place to start as any, as Manziel led a huge second-half comeback even with receiver Mike Evans being a nonfactor — a fiery Manziel coached up his teammates on the sidelines, delivered some wild Johnny Football scramble plays (as well as some plays he’d probably like to have back), and made some gorgeous throws.

I loved watching Manziel play at Texas A&M. He did things I’ve never seen a quarterback do, which was all the more surprising given how intimately familiar I am with the system he ran in college. I watched him grow over two years, particularly as a passer, evolving from his first start against Florida through that final game against Duke.

Despite knowing and appreciating Manziel’s game, I can’t say whether he’ll be a successful NFL quarterback. It could go either way. And that’s why it’s so important to watch Manziel play. He’s a different kind of quarterback prospect, and teams can’t go down the usual checklist and evaluate him in the traditional way. If that’s the only draft approach that makes a team comfortable, that team isn’t going to touch Manziel. The team that does draft him will likely feel confident it knows the answers to two tough questions: Can Manziel, who possesses some of the most unique and incredible gifts any college quarterback has ever displayed, add a layer of refinement and consistency to his game? And can the guy who makes the special look routine also make the routine look special?

The 2014 draft process isn’t the first time Manziel has needed to win over doubters. He was an award-winning quarterback at Tivy High in Texas, but he was only a three-star recruit, and while he flirted with Chip Kelly and Oregon before ultimately signing with Mike Sherman and Texas A&M, he didn’t get an offer from the University of Houston. Cougars head coach Kevin Sumlin and offensive coordinator Kliff Kingsbury weren’t convinced Manziel was a fit for their system, a version of the vaunted Air Raid offense originally developed by Mike Leach and Hal Mumme and evolved by Sumlin, Kingsbury, and others. Previous Air Raid quarterbacks, including Case Keenum at Houston and Graham Harrell and Kingsbury at Texas Tech, were traditional pocket passers who ran little and threw a lot, often racking up video-game numbers despite not being top-tier NFL talents.

When Sumlin took over for Sherman and brought Kingsbury with him to A&M, it wasn’t clear Manziel would get the starting nod. And Manziel did himself few favors during Sumlin’s first spring practice, committing a flurry of turnovers as fellow Aggie Jameill Showers emerged as the front-runner. But Sumlin kept the QB competition open into the fall, allowing Manziel to decrease the turnovers and increase his understanding of the offense. Ultimately, Sumlin and Kingsbury handed the Air Raid keys to a quarterback they weren’t sure they wanted out of high school, and built the offense around him. Manziel’s electric Heisman season was the result.

While Manziel was college football’s best player in 2012, he was not its best quarterback. To become that, he needed to improve his touch, his downfield accuracy, and his anticipation. In 2013, he showed skeptics what they needed to see, in the process leading the SEC’s top offense in both points and yards. He personally accounted for six games of more than 400 yards of total offense, including amassing more than 500 against both Alabama and Auburn. What’s more, he did so while totaling about half as many rushing yards in 2013 as in 2012. He delivered plenty of Manziel magic, but more of it came from his arm than his legs.

Manziel is by no means a finished product, but he’s shown an ability to get better. And it’s a good thing, because he’ll need to make even bigger improvements as he makes the leap from college to the NFL. His lower-body passing mechanics can be wildly inconsistent, and he has a tendency to needlessly side-arm throws or pass up open receivers while trying to make an extra play. He also rarely if ever gives up on a play, often to his detriment. That stubbornness and freestyling make Manziel the player he is, but to succeed in the NFL, he’ll need to learn that sometimes a quarterback has to throw the ball away. Doubters looking for ammo need only point to last season’s game against LSU, when an injured Manziel looked downright bad at times.

Johnny Football has built his legacy on extremes, so it’s fitting that he’ll likely end up a superstar or a bust, with little room in between. Sure, he could flop. But he’s also smart and exceptionally athletic, and he’s clearly a quick study. And while he’s short, his natural gifts are as rare as they come. If Manziel works hard, and if he winds up on a team that’s willing to adapt to him rather than force him to change his game, there’s no reason he can’t be Johnny Football in the NFL.

Bortles, Bridgewater, and Manziel all need work, but they also have the potential to lead an NFL team to championships if they wind up in the right situation and get a chance to develop. They also face the same problem: The NFL is no longer a league where quarterbacks are afforded the luxury of patience, and that now-or-never mentality affects how teams draft. To succeed amid that climate, often while on a bad team, a young quarterback needs something special to carry him through that learning period. Maybe that’s why my Rorschach test keeps bringing me back to the same young quarterback.

“The single trait that separates great quarterbacks from good quarterbacks is the ability to make the great, spontaneous decision, especially at a crucial time,” wrote Walsh. “The play that was called has broken down and 22 players are moving in almost unpredictable directions all over the field. This is where the great quarterback uses his experience, vision, mobility and what we will call spontaneous genius. He makes something good happen.”

Bortles, Bridgewater, and Manziel can all play, but I’d call only one a “spontaneous genius.” Johnny Football tops my board … but maybe that says more about me than it does about him.