during their NFL game at Levi's Stadium on October 4, 2015 in Santa Clara, California.

A quarterback who led his team to the Super Bowl may be ready to walk away from the NFL

He would be walking away in the prime of his career

There's been a ton of speculation about Colin Kaepernick and why he remains unsigned. Given his national anthem protest, he's too controversial. He's on a vegan diet and has lost weight. He wants too much money.

Now, Peter King at MMQB hears another theory that sounds credible: Kapernick is done with the NFL. King wrote:

I spent a long draft weekend with the Niners in California, and there are those in the building who think Kaepernick might actually rather do social justice work full-time than play quarterback.

RELATED: One coach believes Colin Kaepernick can still win championships

There's some evidence of that. Kaepernick has purchased a place in New York City, and has already engaged in social activism work. For example, he gave 100 men's suits to a parole office so recently released prisoners would have something to wear on job interviews, King noted. He also wrote:

It's crazy that a quarterback who four years ago was coming off a Super Bowl appearance and looked to be a long-term answer has no team now and no hot NFL prospects that anyone can see.

Wouldn't it be something if the narrative has been wrong the whole time — that's it's not that the NFL doesn't want Kaepernick,  but it's Kaeprnick who doesn't want the NFL. King is right — he's still  talented enough to play. A League that embraced a man who beat a woman in Joe Mixon surely would give Kaepernick another shot — if he wanted one.

It's beginning to look like he doesn't.