A) Some sports are a safe place for LGBT athletes, others are not. It is difficult to tell which is which, but in the upcoming NFL season we will get to see just how safe the league is for Michael Sam. In the NBA, it is likely much safer; had Jason Collins come out in 2002, when he was a key role player in a New Jersey Nets team that made it to the NBA Finals, it would have been a far more interesting story. The Nets would not have wanted to cut their starting center, and the players would have loudly objected if the organization tried. However, by 2013, Collins was in his mid-30's, and his offensive game, already a weakness in his prime, had deteriorated to near-uselessness. He just wasn't good enough to land a starting role, and has proven to be barely adequate as a third-string center now that he has been signed by the (now Brooklyn) Nets. As Michael Sam is a rookie, it will be extremely fascinating to keep an eye on his progress. As it stands, we still await the first high-profile, active, in-his-prime gay male athlete that the media is truly craving.
B) It's hard to know if modern top-tier pro sports are safe places because of the lack of transparency inherent in the running of these organizations. Locker room drama tends to stay in the locker room and management has gotten extremely adept at keeping crises in house before they spiral out of control. There are notable exceptions, such as in college basketball, which has less money than the pros and thus less power to keep drama out of the headlines. This was a problem that Penn State simply chose to ignore for almost three decades under head women's basketball coach Rene Portland, who set about making her program distinctly unsafe for lesbians. This doesn't happen very often in modern times, especially in women's basketball, where shooing lesbians away from your team will invariably make your team worse than it could be. Sport culture has traditionally been very unsafe for LGBT people, but the world is changing, and many athletes currently active in the pros have expressed solidarity with or support for the LGBT community (http://www.lgbtqnation.com/2012/10/espn-poll-reveals-where-pro-athletes-stand-on-same-sex-marriage).
While sport may not yet be fully safe for LGBT players, it also must be brought up that even if some pro athletes are gay, it probably isn't that many; according to Wikipedia, less than 4 % of Americans in total identify with some aspect of the LGBT acronym. You can reasonably expect that percentage to much lower in athletes, as gay men are less likely to be interested in sports relative to straight men thanks to centuries of homophobia running unchecked in sport.
C) The only effective strategy I've heard of to combat ignorance is education. Eventually, there will be more gay athletes and the homophobes will have to learn to accept their teammates for who they are, if only to make playing football with them easier. In fact, now that Jason Collins has actually been playing for a couple of months, it has become clear that the furor over his being gay in a locker room with a bunch of straight men has been for naught; the Brooklyn locker room has been drama-free, and Collins was able to parlay two ten-day contracts into one that keeps him in Brooklyn until the end of this season (http://www.netsdaily.com/2014/3/15/5511554/brooklyn-nets-officially-sign-jason-collins-for-rest-of-the-season). As far as his teammates are concerned, his love of basketball is all that matters.
