Armour: Another Tim Tebow try that is certain to fail

Tim Tebow is not, nor will he ever be, NFL starting quarterback material.

Now that the former Heisman Trophy winner and cult hero is getting another crack at the NFL, there's a fresh wave of Tebowmania. Never mind that the Philadelphia Eagles already have three other quarterbacks, all of whom have actually thrown a pass in the past two seasons — unlike Tebow.

Or that his contract is more suited for kicking the tires than handing over the keys to the franchise. Or that Eagles coach Chip Kelly once said Tebow wouldn't fit in his system.

Tebow has a large and very passionate fan base, many of whom admire him for reasons that have little to do with football. Which is fine. But that doesn't make him a starter. In fact, even backup duties would stretch the outer limits of his capabilities.

"If you've spent any time around him whatsoever you're pulling for him," said Virginia Tech offensive coordinator Scot Loeffler, Tebow's quarterbacks coach his final season at Florida.

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The sad truth is that success in college is rarely a guarantee of success in the pros — quite the opposite in many cases. With the exception of Cam Newton, quarterbacks who won the Heisman have generally been a bust in the NFL.

Tebow, Johnny Manziel, Matt Leinart. Even Robert Griffin III and Carson Palmer have been inconsistent after strong starts. (The verdict is still out on Sam Bradford, Tebow's new teammate, who has been plagued by injuries.)

Part of that is because the competition is so much fiercer in the NFL than it is in college. Yes, even in the Southeastern Conference. But the game is different, too. Faster. More sophisticated. More complicated. Mistakes that players could get away with in college become turnovers and touchdowns in the NFL.

There's a reason no team has shown interest in Tebow since the New England Patriots cut him during training camp in 2013. The skills that made him so captivating in college — the running back-like rushing totals, hair-on-fire scrambles and high-risk passes — simply don't work in the NFL.

Tebow's arm has never scared anyone. When he took Denver to the postseason in 2011, his completion rate was 46.5%. Yes, you read that right. That would have put him 79th in the NFL last season. In other words, he would have ranked behind Christian Ponder, Case Keenum and Josh McCown.

Even Manziel had a better completion rate.

Working with quarterbacks guru Tom House, as Tebow reportedly has done, should improve his fundamentals and, thus, make him more accurate. But it won't necessarily fix his decision-making, which also was suspect.

Tebow would often hold onto the ball for too long when he found himself under pressure, making him susceptible to sacks. His 33 sacks in 2011 are a cause for concern, but it's the 225 yards he lost on those sacks that are the larger cause for alarm.

He can stretch defenses with his legs — he ran for 660 yards and six TDs in 2011 — but the NFL has no use for a one-dimensional quarterback.

"I look for a quarterback who can run and not a running back who can throw. I want a quarterback who can beat you with his arm," Kelly said in 2011, according to Grantland.com. "We are not a Tim Tebow type of quarterback team. I am not going to run my quarterback 20 times on power runs."

Granted, Kelly was the Oregon coach when he said that. But he didn't abandon his high-powered offense on the trip from Eugene to Philadelphia.

It's more likely Kelly would use Tebow on red-zone or short-yardage plays, taking advantage of his rushing ability. But that's part-time duty, and it's doubtful Tebow gave up a promising career as a television analyst just to play a handful of snaps each week.

"I just know this: I know the guy is probably in top-notch physical shape. I can promise you he's been working on his trade and his throwing mechanics," Loeffler said. "Knowing him, I know he'll put every ounce of energy into it."

But passion and work ethic have never been Tebow's shortcomings. Being an NFL quarterback requires a certain skill set, and Tebow doesn't have it.

GALLERY: TIM TEBOW'S CAREER IN PICTURES