From late April 2013 to early May 2014, gay and lesbian athletes welcomed breakthrough after breakthrough in the historically closeted world of sports.

Journeyman basketball center Jason Collins came out as gay and later signed a contract with the Brooklyn Nets, making him the first openly gay player to get into a regular-season game in the NBA, NFL, NHL or MLB.

A few weeks after Collins’ announcement, Robbie Rogers debuted for the Los Angeles Galaxy, breaking a similar barrier in Major League Soccer. That October, U.S. women’s soccer superstar Abby Wambach married her longtime girlfriend.

Finally, in football, SEC defensive player of the year Michael Sam became the first out player to be drafted when he was selected by the St. Louis Rams in May 2014.

But if some were hoping the events of 2013 and 2014 would spark a wave of professional athletes coming out, little headway has been made. Since Sam was drafted, no active players have done so from any of the four major sports leagues. The closest have been players like David Denson, a minor league prospect for the Milwaukee Brewers who quit baseball this past spring, and retired NFL lineman Ryan O'Callaghan, who came out on June 20.

What gives? Are professional athletes worried about discrimination? Do the perceived barriers to coming out as an athlete – not being signed by skittish general managers, not being accepted by teammates, being labeled a “distraction” by coaches or the media – still exert undue influence?

The answer is a nuanced one. Read more via the Conversation