Thearon W. Henderson/Getty Images

With the NFL draft hype train rolling through the pro day schedule at full speed, there's a potential top-10 quarterback we've barely heard anything about—and what we've heard is all over the map.

Cleveland Browns head coach Mike Pettine called him "the best natural thrower in the draft," per Mike Huguenin of NFL.com. Bleacher Report NFL Draft Lead Writer Matt Miller has him going No. 8 overall, and three of four CBSSports.com experts have mocked him that high, or even higher.

He's not on Mel Kiper's Big Board (subscription required), though, or in Todd McShay's Top 32. The two ESPN experts aren't alone in overlooking him; neither Sports Illustrated's Don Banks nor USA Today's Nate Davis project him to be drafted in the first round.

Who is this mystery man?

David Carr's little brother.

All of the Tools

Derek Carr isn't going to go No. 1 overall like his big brother did back in 2002.

At 6'2", 214 pounds, Derek doesn't have the prototypical size of a Blake Bortles. The competition he faced in the Mountain West Conference can't compare to the elite defenses Johnny Manziel picked apart week in, week out.

Carr put up bonkers statistics, throwing for 5,083 yards and 50 touchdowns as a senior—but he did it in a shotgun-based offense that didn't call for him to make a lot of vertical throws, unlike the pro-style West Coast offense Teddy Bridgewater ran.

Yet, all the tools are there.

His size isn't elite, but he's the exact same size as Bridgewater (also 6'2", 214 pounds, per NFL.com), bigger than Manziel and comparable to recent top quarterback prospects like Matthew Stafford.

He's also an excellent athlete, finishing among the top quarterbacks at the combine in the 40-yard dash (4.69 seconds), vertical jump (34.5 inches) and 20-yard shuttle run (4.20 seconds). Unlike Manziel, Carr used his athleticism mostly to escape pressure and throw, or on designed rollouts. Per College Football Reference, Carr had just 190 rushing yards on 164 career scrambles.

His arm is more than strong enough to zip every NFL throw, and he has a quick, compact wrist snap of a throwing motion. Let's watch and enjoy:

DraftBreakdown.com

That ball flew 50 yards downfield, from the right hash to beyond the left numbers. Some rough Pythagorean math suggests that's about a 57-yard throw, dropped right in the breadbasket of his streaking receiver.

No wonder some experts see in him the makings of a quality NFL starter.

Less Than the Sum of His Parts

There's a reason Carr isn't going No. 1 overall, though: Poor footwork keeps him from using that incredible arm talent to its full potential.

Here's an extreme example of one of Carr's worst habits:

DraftBreakdown.com

In trying to throw around a defender who jumped the snap, Carr ends up turfing a bubble screen to a receiver who can't believe it.

Let's take a closer look at why that pass misfired.

After receiving the snap, Carr firmly plants both feet in a random direction. Then he pulls his arm and torso back, without moving his feet. Finally, he snaps his elbow and wrist forward and barely even moves his hips or shoulders:

DraftBreakdown.com

It's almost impossible to be consistently accurate with footwork and mechanics like this. A quarterback should step toward his target, open up his hips and allow them to pull his shoulders and arm through the pass. His weight should transfer completely from the back foot to the front.

Instead, Carr routinely plants both feet and leverages his upper body against his lower body. He rotates his torso more or less depending on where he's trying to throw and relies on his release and arm strength to get the ball there.

Watching Carr's cut-ups at DraftBreakdown.com reveals that he sprays the ball to all sides of the field with a fixed base, like one of those rotating lawn sprinklers. In the Las Vegas Bowl against USC, his poor footwork led him to miss four or five wide-open receivers, and he threw many more uncatchable balls.

Here's one of those problematic passes:

DraftBreakdown.com

Again, Carr relied entirely—almost comically—on his arm for this throw. Watch his motion, from both angles, and you'll wonder how he generated enough power to badly overthrow this go route:

DraftBreakdown.com

He starts off, as he usually does, with his feet too wide. That first frame is how his legs should look after he steps into a pass, not before he goes into his motion. Then, he steps backward with his left foot and goes up on his toes, resulting in a bizarre throwing position (circled in red).

We can clearly see his hips and shoulders don't rotate at all; this pass is all arm. Not only is it difficult to get any kind of consistency or accuracy throwing that way, but it would also seem to put a lot of stress on his arm.

Carr's bad habits get worse under pressure.

When defenders break through his protection, he often runs—and he often throws off his back foot while falling away. He also, as seen in the miss above, seems to get sloppy when the game situation gets more intense. His disastrous performance in that bowl game has to worry teams looking to build their offense around him.

Coach Him Up

Carr's big brother, David, couldn't escape constant questions about his throwing motion.

Here's an ESPN.com pre-draft scouting report:

Negatives: Semi-sidearm, unusual, three-quarter throwing motion. Has a very low release point, about shoulder level. Will get balls batted down, which could be huge problem, since so many teams use so many three- and five-step drops. Is basically a line-drive passer.

Meanwhile, Derek seems to be getting a pass, drawing raves for outshining a very weak group of Senior Bowl quarterbacks.

Of course, for every offensive head coach or coordinator who looks at Carr's film and sees a guy with a lot of problems, three will look at him and think they can coach him up.

There's no question Carr has the tools to be an NFL starter, maybe even a great one. It's easy to see why many experts and teams see him as no less of a prospect than Bridgewater, Bortles or Manziel.

His mechanical issues seem to be a result of never needing good mechanics to throw the ball well enough to win. However, there's a big difference between "enough to win" in the Mountain West and "enough to win" in the NFL.

Whichever team drafts Carr will need to invest in rebuilding his mechanics, so they don't break down when opposing defenses turn up the pressure.