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It was 2013. Wes Welker was with the Broncos, and Sports Illustrated came to do a cover shoot for a story on what figured to be a scary Denver offense. The players in the shoot were Peyton Manning, Eric Decker, Demaryius Thomas and Welker.

Manning didn't know it, but Welker and the receivers had organized a nice little prank on him, conspiring with the SI photographer and the head of Broncos media relations, Patrick Smyth. The receivers showed up shirtless—just pants and shoulder pads. They told Manning that was how they were doing the shoot, and he needed to, too. Manning was not happy. At all. He protested and refused to remove his shirt. The receivers insisted. Manning said no way. Back and forth it went.

"He was hedging, like, 'Maybe a few years ago, but not now,'" Welker said in the SI piece, written by Chris Ballard. "And then he was asking Patrick Smyth about it, and I'm thinking, 'C'mon, don't back out on me now!' ... Finally [Manning] said, 'No way, I'm just not going to do it. You guys take the photo without me.' It was hilarious."

It's also the type of story you'll often hear from and about Welker, one of the great teammates—and pranksters—in NFL history.

That year, the Broncos set regular-season records for touchdowns and points scored. Welker did more than just initiating pranks. As usual, he was a quarterback's best friend. He had nine touchdowns through the 11th week of the season, more than he had all of the previous season with Tom Brady.

It was all there.

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Then, on Nov. 17, Welker suffered a concussion in a game against the Chiefs. Then, 21 days later on Dec. 8 against the Titans, he suffered another. Then, after missing the remainder of the 2013 regular season, yet another concussion, on Aug. 23 during a preseason game against the Texans.

The second of those was typical of the type of head injury Welker has been prone to. He was crossing the middle and took a nasty shot up high. He'd miss the remainder of that regular season.

The third was when teammates began to worry about his future, from what I'm told by people in the Broncos organization.

Wes Welker Career Statistics Year Team Catches Yards TDs 2004 SD/Mia 0 0 0 2005 Mia 29 434 0 2006 Mia 67 687 1 2007 NE 112 1,175 8 2008 NE 111 1,165 3 2009 NE 123 1,348 4 2010 NE 86 848 7 2011 NE 122 1,569 9 2012 NE 118 1,354 6 2013 Den 73 778 10 2014 Den 49 464 2 Pro-Football-Reference.com

Welker returned in 2014, starting eight games for the 12-4 Broncos. But he is now in limbo. His contract expired after the season, and he is an unrestricted free agent without a new home.

So why isn't he playing? Why is one of the best receivers in recent NFL history, and by all accounts a fantastic teammate, unsigned?

One general manager told me that his team strongly considered signing Welker, but that "there was great concern about his concussion history."

Here's the thing: The three concussions in a nine-month span were widely discussed, but it's impossible to say how many concussions Welker has had beyond that. Teams familiar with Welker's medical history say they believe he has had at least six concussions and as many as 10. Only he knows for sure. And it's possible he may not know the full number.

This is the only reason Welker isn't being picked up. In some ways, fair or unfair, he has become one of the concussion poster children. And teams don't want to be seen as not caring about concussion issues at a time when so much public attention is focused on the issue. They don't want to be the team that gave a concussion-prone player a chance to get his next concussion.

For his part, in interviews over the past few months, Welker has said that he's healthy and doesn't intend to retire. In April, after meeting with Dr. Stanley A. Herring—a member of the NFL's Head, Neck and Spine Committee—Welker told 9News' Mike Klis that everything was fine:



I knew there were concerns out there but on top of that I wanted to know for my own peace of mind. If there was something wrong, I wanted to know. The doctor said some people are able to take those hits. They get up and are able to come back from them. And there's some people who get them and they're never the same. For me, everything came out all good. My cognitive tests were good. All kinds of tests came out good. I had a trip to Miami and [their] doctors said everything looked good. ... ... I am 100 percent committed to keep playing. I feel like every day that goes by, the chances are less so. But I want to play. I've enjoyed my time away. I've enjoyed spending time with my wife. But I'm itching. I miss the locker room. I know once the season starts I'll be dying if I'm not playing.

Welker emphasized again in June that he wanted to keep playing, saying on CBS Boston's The Sports Hub's Toucher & Rich show:

At times you're sitting there and thinking, "Well maybe I should [retire]." I think it's just people kind of [pressuring you], but the more you think about it, and you're away from it, I'm not ready to. I still feel good. I still feel like I have some really good football left in me. I've always said [I'll play] until the wheels fall off.

In a different era of concussion awareness (say, five years ago or so), if Welker still wanted to play, he would have been on a team by now. He is 34, and while his production has declined over the past two years, his career overall has been so stratospheric, teams would have signed him. He's only two injury-filled years removed from being one of the best receivers in the sport.

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But the sport has drastically changed in recent years because of concussion fears. A player with a concussion history like his now will have trouble finding work.

This isn't to say no team will sign Welker. I'm told there are teams interested. Two of his old teams, the Patriots and Broncos, are not among them, apparently; another of his old teams, the Dolphins, seem like a good fit, as do the Ravens.

One general manager said teams that are interested might be waiting for more time to elapse, more separation from the last known concussion—regardless of what Welker says about his health.

There are other teams that are terrified of Welker's concussion history and won't go near him.

So, here we are with one of the great receivers and special teams players of all time.

There is something else interesting regarding Welker, who could not be reached for comment. While other players with concussion histories contemplate their futures in ways we've never seen in football previously—with some guys even retiring in their mid-20s—Welker still wants to play.

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This isn't to say Welker hasn't done soul-searching on the topic. He likely has. But he seems to have decided to push on after concussions at a time players are doing the opposite. The 49ers had two players retire in Chris Borland and Anthony Davis because of concussion fears (though it might be more accurate to say that Davis is on a concussion sabbatical).

Former Carolina tight end Ben Hartsock told Sporting News' David Steele of the Borland and Davis retirements:

[They] wouldn't have happened before, because they didn't know. Ten or 15 years ago, this issue wouldn't even have come up. If you had post-concussion symptoms, how would you recognize them? If you had concussions, how would you know? But the awareness of concussions has increased these last few years. The landscape now is such that players know more and can make their own decisions.

It seems Welker has made his decision to play. He has answered the question: At what cost?

Now teams have to answer that same question.

Mike Freeman covers the NFL for Bleacher Report.