View Photo Gallery: Peyton Manning is a free agent — and a somewhat risky one, given that no one has really seen him throw.

Peyton Manning may well be the most exciting, most highly coveted, most “mostest” free agent to hit the market in the NFL, but he’s also one of the riskiest.

His father, Archie, has watched him throw and says he “looked like Peyton” again after multiple neck surgeries. But other than a grainy 27-second video, he hasn’t actually shown what he can do or how well his triceps nerve and arm strength are recovering. He did not throw for the Indianapolis Colts, who released him Wednesday, and said he did not pass a physical.

For the 12 teams that reportedly are interested in signing Manning, that’s not prohibitive and the gamble could be minimized with an incentives-laden contract. The NFL Network raises the possibility of a Peyton Manning “pro day” workout/media frenzy, but Jason La Canfora reports that Manning’s agent has not indicated whether he will “hold one workout for teams, hold individual workouts, or just make visits.” The uncertainty may be particularly troubling for the Miami Dolphins, who are going all in on the Manning Sweepstakes. After all, they passed on the chance to sign Drew Brees in 2006 because he had had shoulder surgery and, Armando Salguero writes, “that memory may still be roaming the halls at Dolphins camp.”

The risk is more significant for Manning himself, but his doctor has cleared him to play and his father has said he is not concerned about the possibility of a catastrophic injury. Other medical experts, who have not treated Manning, concur.

Wellington K. Hsu, a spine surgeon and assistant professor at Northwestern, told USA Today that the area of the single-level anterior fusion “is probably stronger now than it was before the surgery because he has a solid, bony fusion.”

The larger issue is Manning’s arm strength, according to Dr. Robert S. Bray Jr. of the DISC Sports & Spine Center. “His risk really is very low,” Bray told the Boston Globe. “If I was a team, I'd ask, ‘Did [the fusion] heal? Do you have a CAT scan that showed it healed? Is the rest of neck in pretty good shape?’ If those two answers are yes, then it gets down to, ‘Okay, get out on the field and show me you can perform,’ because it will only get better from here with time.”

As for nerve regeneration, “nerves are just wires and the muscle is where the wire plugs into,” said Dr. Charles Bush-Joseph of Midwest Orthopaedics at Rush University told the Globe. “Obviously he's got all the intelligence and the skill set. It's a matter of strength. Can he get his arm to do what his mind and eyes want him to do?”

There’s an awful lot — for his suitors and for Manning himself — riding on that.

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