Not all athlete speech is offensive. Some athletes do speak out for worthy political ideals, even if it comes with a price. Chris Kluwe, formerly a punter for the Minnesota Vikings, was an outspoken advocate for marriage equality. He was released by the Vikings last spring amid obvious questions about any connection between his activism and his release. Although Kluwe has always said some version of "I don't know" when asked about the connection, in a piece on Deadspin Thursday he says he is "pretty confident" his activism was the reason he was fired.
In the article, Kluwe describes not-so-subtle pressure from (now former) Vikings head coach Leslie Frazier and GM Rick Spielman to stop speaking out on marriage equality or gay rights and outright anti-gay bigotry by special teams coach Mike Priefer, including telling a roomful of players "We should round up all the gays, send them to an island, and then nuke it until it glows." The Vikings deny that Kluwe's release was based on anything other than his performance, but have promised to investigate (owner Zygi Wilf is a strong supporter of marriage equality). Priefer issued his own statement "vehemently" denying Kluwe's allegations. Stay tuned; this could cast another interesting light on athlete speech and the culture of NFL locker rooms.
[Update: The Vikings have hired a former chief justice of the Minnesota Supreme Court and a former DOJ attorney (who previously lead the investigation into misconduct by Fiesta Bowl officials) to conduct the investigation. If I had to predict an outcome, it would be that there will be insufficient evidence to support Kluwe's allegations of a retaliatory firing, but that if any evidence corroborates Priefer's "nuke it" comment, he will lose his job in Minnesota (although almost certainly will coach again, because that is just how football works).]
One other thing I'll highlight from Kluwe's original piece. He describes a conversation in which Frazier strongly urged him to stop speaking on this, allegedly saying, "'a wise coach once told me there are two things you don't talk about in the NFL, politics and religion.'" Given the blatant role that Christianity plays in football, including in the NFL, this may be one of the dumbest things ever said.