I think the quarterback of tomorrow is going to be better than we are today, and he will be able to do a zillion things, including scrambling. He's going to have the ability to throw from the roll, the moving pocket, the drop-back pocket, the bootleg and the busted play.
-- Fran Tarkenton, Sports Illustrated, 1967
Critics of Tim Tebow's pro prospects are legion and seemingly as vocal as his fervent fan base.
To hear his doubters -- yes, including ESPN's own Mel Kiper Jr. -- tell it, the Denver Broncos' rookie quarterback has many flaws:
To sum them up, he has questionable aim, sloppy footwork and a slow delivery. He'll struggle reading NFL defenses while taking snaps from center. He runs recklessly and much too often.
Some claim he's not worth one of the Broncos' 2010 first-round draft picks -- especially at the cost of three selections.
Still, Tebow owns the type of athleticism that has allowed NFL quarterbacks who were not classic drop-back passers to thrive. At some points in their careers even Hall of Famers Fran Tarkenton, Roger Staubach and Steve Young had their skills questioned because they did not seem to fit the conventional mold. One usual complaint: They ran recklessly and much too often.
Their mobility not only made them different but eventually helped them excel. ESPN.com recently surveyed some of the NFL's best mobile quarterbacks -- as defined by the career rushing list -- for their thoughts. The consensus: As long as Tebow is allowed to get on the good foot, he can be a factor as a running quarterback -- and that's a great start.
"The value of a running quarterback, somebody who can pick up four or five first downs a game, is huge," said Stanford coach Jim Harbaugh, a veteran of 14 NFL seasons and ranked No. 9 (2,787 yards) on the quarterback career rushing list.
"That keeps drives alive and leads to points. That's a huge asset …. [Tebow is] a winner. He's got tremendous athletic instincts. I'm sure the Broncos know what they're looking at it in terms of accuracy, decision-making and timing."
The right environment for success?
As Broncos head coach Josh McDaniels grooms Tebow, no doubt the former University of Florida star's skills as a runner (2,947 career rushing yards, 57 rushing touchdowns) will be exploited in some way.
Can Tebow succeed in his transition from Florida's run-option, shotgun offense to taking snaps under center in Denver's pro-style attack?
The veteran quarterbacks ESPN.com surveyed stressed that Tebow can succeed if given the time and coaching he needs. No one is booking space for him in Canton. But nobody dismissed his chances to be a good player, either.
"I know that Tim Tebow is not the prototypical quarterback. I wasn't either," said Tarkenton, the Pro Football Hall of Fame passer who played 18 NFL seasons.
"Neither was Roger Staubach, even Bob Griese wasn't. I had my own style of play and did OK."
Tarkenton excelled in the 1960s and '70s with his whirling dervish dashes whenever his passing pocket collapsed. A 6-foot, 190-pounder who sometimes "willed the ball" to his intended receiver, "Scrambling Fran" was not a talent scout's dream on paper. Still, Tarkenton rewrote pro football's record books with the New York Giants and Minnesota Vikings, leading the Vikings to three Super Bowl appearances doing things his way.
From what he's seen of Tebow, Tarkenton is impressed. He says the key to Tebow's NFL success will be whether he's given the right coaching and the freedom to improvise when he has to -- a hallmark of a mobile quarterback.
"The only thing that will hurt him is coaches. Most coaches don't understand quarterbacks. Don't try to coach him into what he's going to be. That would be a disaster," said Tarkenton, whose 3,674 career rushing yards rank him fourth in NFL history among quarterbacks.
Tarkenton believes Tebow is in the ideal situation under quarterback guru McDaniels' tutelage.
The key to Tebow's development will be allowing him to do what he does best, Tarkenton said.
"Peyton Manning can't do what Tim Tebow does, and vice versa. … The quarterback position is about playmaking, it's about leadership. It's a complex position you can't test for."
Don't sweat the technique
Some have criticized Tebow's long, winding left-handed delivery of his passes and his tendency to "drop" the football -- holding it close to his chest before firing -- that might make him more susceptible to sacks and deflections. Even though Tebow set an SEC record for career passing efficiency at Florida, he has tried to speed his release in preparation for his pro career.
His passing technique has called to mind comparisons to former first-round draft pick Byron Leftwich. After initial success as a Jacksonville Jaguars 2003 selection, Leftwich is a journeyman who is now in his second stint with the Pittsburgh Steelers.
I look at Tim Tebow's throwing motion and it doesn't look that much different than Steve Young's, if you put them next to each other.
"-- Stanford coach and former NFL QB Jim Harbaugh
However, another quarterback comes to mind when Stanford's Harbaugh watches Tebow.
"I look at Tim Tebow's throwing motion and it doesn't look that much different than Steve Young's, if you put them next to each other," said Harbaugh.
"Steve Young would drop the ball when he threw it. And he's a Hall of Fame quarterback. To me it's more important to be natural than it is to shave a tenth of a second off the time it takes to get rid of the ball."
In 2009, the Super Bowl XXIX MVP told The Los Angeles Times that he was flattered by a reporter's suggestion that Tebow recalled, er, a younger Young.
Young, now an ESPN analyst, told the newspaper that Tebow's delivery might be the only thing about the Florida star he questioned.
"Passing in the NFL is delivering the ball at the right time in the right place," said Young, whose 4,239 yards ranks second only to Randall Cunningham (4,928) on the NFL quarterbacks rushing list.
"If you can't do that, you'll find your way out of the league. To me, that's the only issue. Everything else is comical to me. 'OK, what don't you see?'"
That said, Harbaugh believes too much has been made of Tebow's passing technique.
"I don't mess with a guy's throwing motion," said Harbaugh, who starred for five teams and led the Indianapolis Colts to the 1995 AFC Championship Game. "It's more mechanics. It's footwork. It's accuracy and decision-making."
Harbaugh said the key to Tebow's exploiting his skills as a running quarterback will be learning when to run. He'll last longer and be more effective if he's patient enough to read as many progressions as possible before high-tailing it.
"Say he only looks at one read and then runs. He can be effective that way," Harbaugh said. "[But] I don't think that's the most effective way to be a quarterback. … Ideally, you want to be able to get through three reads and then, if [the open receiver is] not there," run for daylight.
Resist a position switch
Kordell Stewart faced some of the same doubts about his NFL quarterbacking prospects when he entered the league as a Pittsburgh Steelers second-round draft pick in 1995.
In Colorado's offense, Stewart displayed great athleticism but questionable accuracy. Even as Tebow racked up a 67 percent career pass completion percentage in Florida's shotgun offense, scouts have their doubts about his eye.
As one NFL.com scouting report put it: "[Tebow] has a strong arm, but his accuracy has been inconsistent over the years as he often ends up throwing the ball when on the move."
Likewise, "I was a great running quarterback with a strong arm. Inaccurate. Can't read a defense," Stewart, also an ESPN analyst, described the scouting report on himself as rookie.
Stewart's willingness to do whatever it took to contribute to the Steelers' success while waiting for a chance to be a starting quarterback allowed him to develop into a hybrid. He became a receiver/quarterback/running back/punter early in his career. Stewart earned the nickname "Slash" for his multiple skills and playmaking ability.
His versatility helped the Steelers reach Super Bowl XXX. Later, Stewart got his chance to play quarterback exclusively and led the Steelers to the first of two AFC Championship Games under his helm.
But Stewart cautions Tebow, who at 6-3 and 245 pounds seems built to play the H-back tight-end/fullback hybrid position, to resist any move to push him out of the quarterback mode. McDaniels insists that's moot, and Tebow was drafted to be only a quarterback. Still …
Playing H-back, Tebow "would get hurt. Bad," Stewart said.
Stewart maintains that even if Tebow struggles while competing in the Broncos' quarterback derby that includes incumbent Kyle Orton, 2009 draftee Tom Brandstater and former Cleveland Browns quarterback Brady Quinn, the rookie should keep the faith.
"He has everything that you need in a quarterback in coming to the next level. It's just a matter of getting him the experience that every player in the National Football League deserves to go out and fail, learn from the mistakes and just get better from it," said Stewart.
Be a crash-resistant 'Ferrari'
Ranking eighth on the NFL quarterback career rushing list with 2,874 yards, Stewart had the kind of speed that allowed him to score from 80 yards out after taking a snap. Tebow's 4.72 40-yard dash time at the NFL combine won't give defensive backs night sweats, but the prospect of making a solo, head-on tackle on him might.
Many of the quarterbacks ESPN.com interviewed cautioned Tebow will have to learn, as every pro passer does, that it's better to live another day rather than take on tacklers as fearlessly as he did at Florida.
Bobby Douglass was a left-handed, hard-running quarterback for 13 NFL seasons, many with the Chicago Bears. Douglass sometimes ran without a helmet in his fury to gain yards.
If Douglass were coaching in the NFL, he'd not only like to have Tebow -- he'd want to clone him.
You get it to 120 [mph] real quick and then shut her down. That's Tim Tebow. He's not a Pinto. He's a Ferrari.
"-- ESPN analyst and former NFL QB Kordell Stewart
"I'd love to have two or three [quarterbacks] who can move like he does. Give me a quarterback who can take a little bit of punishment," said Douglass, who said he expects the Broncos will exploit Tebow's running ability inside the red zone.
Still, "like anything else in life, you have to pick your place, a time and place to do it," said Douglass of Tebow running out of the pocket.
"If he gets caught in a situation, he can lower his head and run over somebody. You're not going to get hurt any more [than you would otherwise] if you give the blow first."
Stewart also says Tebow shouldn't abandon being an aggressive runner. He would just be wise to pick his spots.
"He's like a Ferrari. [Do] you put it on the highway and run it at 40 miles per hour just because the speed limit says 40 miles per hour? Heck no! You get aggressive every once in a while and find your spots," said Stewart, who scored 38 career touchdowns rushing.
"You get it to 120 [mph] real quick and then shut her down. That's Tim Tebow. He's not a Pinto. He's a Ferrari."
No one runs forever
Two seasons into his NFL career, New England Patriots quarterback Steve Grogan gave defenses fits with both his arm and feet.
In leading the Patriots to an 11-3 record in his first full season as a starter in 1976, Grogan accounted for 30 touchdowns. He passed for 18 scores and ran for 12 others.
As Tebow hopes he has the right teacher in McDaniels, Grogan learned from a coach who was willing to make the most of his athletic skills. Patriots coach Chuck Fairbanks came to the NFL after running powerhouse wishbone offenses at Oklahoma.
"I was lucky," Grogan said. "We had option plays in the offense, rollouts with run-pass options. He was never afraid to turn me loose."
In 1978, the 6-4, 210-pound Grogan ran for his season career high of 539 yards. The next season, he recorded another season career high with 28 touchdown passes.
Eventually, "my running skills disappeared when I had some knee problems. But I was able to evolve my game to become a pocket passer," said Grogan, who noted that transition will be an important milestone in Tebow's development.
Tebow's "a winner, he can run, he can throw," said Grogan, who rushed for 2,176 yards and 41 touchdowns in 16 seasons with the Patriots.
"If he does things correctly, his running ability will buy him some time to learn and understand the NFL."
In the meantime, Tebow will have to endure the catcalls amid the cheers as he evolves from holding a clipboard to starting. Even the endorsement of Hall Of Famer John Elway -- the athletic, mobile former Broncos star who ranks among the most prolific running quarterbacks in history -- won't matter. In the end, Tebow must prove himself.
What advice would Tarkenton, who long ago forecast in Sports Ilustrated the coming of unconventional quarterbacks like himself, give Tebow?
"The best thing is to put cotton in his ears and tell him not to listen to the pundits," he said.
"You've got to find the kid that's got the courage to play quarterback, that's more important than throwing motion."
Sheldon Spencer is an NFL editor at ESPN.com.