Great mobile quarterbacks are the unicorns of the NFL. They almost never achieve NFL greatness, and if they do, it's because they've evolved into pocket passers.

They come into the league as explosive athletes, and they're taught to use that athleticism as little as possible. They come into the league as unpolished passers, and they're asked to stand in the pocket and throw.

What is it about the mobile quarterback that intoxicates NFL coaches and general managers? Why won't they then let them do their thing? Why is it so hard for quarterbacks who can run to win on Sunday?

The Coaching Problem

In high school football, the diversity of talent is jaw-dropping: Nearly full-grown Division I talents play on the same field as kids who'll never do anything athletic again in their lives. Defenses can't possibly stop a true dual threat; when you have a special athlete, putting him at quarterback is the quickest way to win.

High school football coaches are like all other football coaches: They want to win. As I discussed in a piece titled "Why African-American Quarterbacks Are Systemically Trained to Abandon Mechanics," transcendent athletes are often shoehorned into the quarterback position, never really taught how to play it. In high school, it works.

This best-athlete-as-quarterback approach has its roots in the early days of football; the Single Wing and its variants used the quarterback as a multidimensional threat.

In the 1930s, New York Giants head coach Steve Owen ran the "A" Formation offense, a Single Wing variant. In 1935, Giants quarterback Ed Danowski led the league in passing yards and finished eighth in rushing yards.

But as the professional game evolved, and the college game along with it, quarterback became a position where field-reading and passing ability was paramount.

In the middle of the 20th century, the "golden boy" passer took over: Quarterbacks had to be a pocket-rooted statue with a rocket arm, taking seven-step drops and launching deep balls.

The problem is, there are a lot more electrifying athletes who can throw "good enough" than rocket-armed passers.

In the '90s and '00s, high school and college coaches began to scheme around this fact: not just putting their best athletes at quarterback, but creating innovative schemes to maximize their talents. Spread formations, unbalanced lines, read options and zone blocking turned dull passers into razor-sharp offensive weapons.

Then these quarterbacks reach the NFL, still no better at passing than when they started.

Mobile NFL Quarterback Cycle of Life Stage I: Rookie

Many mobile quarterbacks never mature past this stage.

Pat White was the second runner-up for Alabama's Mr. Football award his senior year in high school. He went 34-8 as a starting quarterback for West Virginia while racking up 10,529 offensive yards and 103 offensive touchdowns. He was drafted in the second round.

He attempted five professional passes, completing none, in his only year in the NFL.

The mobile quarterbacks who make it past the newbie stage all benefit from good, patient coaching.

Kordell Stewart was eased into the NFL by the Pittsburgh Steelers' Bill Cowher. Stewart earned the nickname "Slash" as a situational quarterback/running back/wide receiver before taking over as a full-time starter in his third season.

As a rookie Steve McNair started only two games for head coach Jeff Fisher, playing in just four. In his sophomore year, he started four and played in nine.

Donovan McNabb was a part-time starter his rookie season, and he ran more often (one carry per 4.6 pass attempts) than any other year of his career.

He caught the NFL's attention with his jaw-dropping juke of Redskins safety Mark Carrier (check the 4:03 mark of this video for a very brief glimpse of it) but was knocked out of his fifth start with a knee sprain.

This is one of the reasons young, mobile quarterbacks fail or become less mobile: injuries.

Whether injuries they suffer rob them of their mobility or their coaches pull back the reins to prevent possible injury, injuries have a major impact on the life cycle of a mobile quarterback.

Mobile NFL Quarterback Cycle of Life Stage II: Dominant Runner

Once mobile quarterbacks survive the newbie stage, they become dominant runners. Their mobility is still intact, and they're not yet reliant on their passing skills. Mobile quarterbacks with successful NFL careers almost always do most of their rushing in their first three seasons as a full-time starter.

In his second, third and fourth seasons combined, McNabb rushed for 1,571 yards and 14 touchdowns; each total is nearly half (45.4 percent and 48.3 percent) of his 14-year career totals.

McNair's story is similar: In his first three years as a starter, he compiled 1,570 yards and 20 touchdowns (43.7 percent and 54.1 percent of his career totals).

Michael Vick is the exception that proves the rule.

Vick's otherworldly running ability—electrifying speed and moves that made him faster than anyone trying to tackle him—allowed him to continue to rely on his feet throughout his career.

He had his best yards-per-attempt rate (9.3) his rookie season, and in his sophomore campaign, he racked up a career-high eight touchdowns while putting up his third-best yardage (777) and fifth-best rate (6.9) numbers.

In his third season as a starter, he ran for 902 yards at 7.5 per attempt. His fifth (and last as a Falcon), he ran for an astounding 1,039 yards at a second-best 8.4 yards-per-attempt clip.

We'll never know how long he could have continued to rush like a running back from under center; his prison term and subsequent signing with the Eagles derailed him into Stage III.

Mobile NFL Quarterback Cycle of Life Stage III: The Peak of Their Powers

The hard truth is, the NFL is a passing league. For all of Mike Vick's amazingness, and for everything he could do for his offense, he couldn't win consistently.

Thanks to injuries, Vick couldn't stay on the field consistently either: He's started 16 games just once in his 10-season career.

Like all mobile quarterbacks, Vick eventually became a pocket passer first and a mobile quarterback second. When he uses his mobility, it's in service of his passing, to get away from the rush.

Unlike high school and college football, a player can't dominate the NFL on raw athleticism...not for long, anyway.

McNabb learned this well; this 14-second scramble-and-throw was still an amazing display of athleticism, but he also avoided taking a hit and gained far more yardage by throwing it:

It's this phase where mobile quarterbacks are at their best. They have two to three seasons where they're a seasoned pocket passer, know how to use their mobility in service of the pass and can still keep defenses worried about their pure rushing skills.

Mobile NFL Quarterback Cycle of Life Stage IV: Not So Mobile

Randall Cunningham was the first modern dual-threat quarterback to hit this phase of his career. After age and injuries robbed him of much of his speed (as well as his starting gig in Philly), Cunningham sat out the 1996 season. He returned, in 1997, to Minnesota, reuniting with his old target Cris Carter.

In 1998, at age 35, long after his amazing running skills had become above-average, Cunningham had the greatest season of his NFL career.

He threw for 3,704 yards, his second-best total ever, and a career-high 34 touchdowns. He also threw just 10 interceptions, the lowest total of his career (when he started at least 10 games).

Former Jaguars quarterback Mark Brunell also began his career as a runner; he ran for 480 yards and four touchdowns in his first year as a starter. But his rushing totals declined for each of the next two seasons, and he never matched that third starting season's rushing yards, let alone the first.

Still, at age 35 and practically immobile, Brunell led the Washington Redskins to a 10-6 season and a playoff victory.

What About Steve Young and John Elway? [Edit]

In a comment to the original version of this piece, Sam Beard noted that Steve Young and John Elway are in the top ten all-time for quarterback rushing yardage, and both of them won Super Bowls. It's absolutely true, and a great point.

I'd considered discussing Young, especially. But he and Elway don't fit the mold of a "mobile," or  "running," quarterback.

John Elway was the son of Jack Elway, a career high school and college football coach who developed spread concepts John executed at Grenada Hills High School under spread innovator Jack Neumeier. See Smart Football for more; Dennis Erickson gives Jack Elway a lot of credit for inspiring Erickson's single-back spread.

Steve Young went to BYU, where he executed the proto-spread Lavell Edwards/Norm Chow offense. Hal Mumme and Mike Leach developed the extreme "Airraid" spread out of concepts first used in that offense.

Both Young and Elway were extremely gifted athletes, and both ran effectively and often in college and the NFL. But both had advanced experience in, and understanding of, state-of-the-art passing offenses, which certainly isn't true of players like Mike Vick and Pat White.

Young and Elway also hit the ground running, so to speak, when it came to passing success: Young had an NFL passer efficiency rating in the triple digits three times in his first five years, seven times overall, and lead the NFL in it six of his first seven years as the 49ers' starter.

Mike Vick hit triple digits once, in 2010, and his highest passer rating during his six seasons in Atlanta was 81.4.

Elway wasn't as surgical as Young, but he was unquestionably a pass-first quarterback: he led the NFL in pass attempts in his third season, with a whopping 605. Elway's arm was the Broncos' entire offense for much of his early career.

Conclusion

Mobility is a great gift to an NFL quarterback. When he can gain yards on the ground, he can help his team win much faster than most pure pocket passers, especially if deployed cleverly by good coaches.

But mobile quarterbacks often trail their pocket peers in development, with high school and college coaches putting much less emphasis on learning passing skills.

Many NFL mobile quarterbacks fail to transition to each "life cycle," their careers never taking off. Many other mobile quarterbacks have their speed taken from them by injury and have to adapt or be finished.

Only with rare talent, excellent coaching and a little luck can a mobile quarterback survive to reach the peak of their NFL powers: that brief two to three seasons where they are just as terrifying through the air as they are on the ground.

No wonder none have ever won a Super Bowl.