Wherever there are people, there is homophobia. There is nothing about sports that makes it special when it comes to how others are viewed; in fact, in might even be more prevalent in professional sports because professional sports assumes a certain gender standard, which unfortunately plays into stereotypes, which is ripe breeding ground of homophobia.
I would not be surprised if there was homophobia in professional sports. I know the gay community and our society have made huge strides, but the fact of the matter is that some people still feel uncomfortable around homosexuals. Athletic and masculine individuals not liking gays isn't that far fetched.
In all sports, from swimming where men are in speedos to football where men are crawling all over each other. When its all said and done men and women both have it in the back of their mind when they are all in the locker room or showers, all they are thinking is "Is he checking me out?" Everyone has it in the back of their mind I just think very few would ever voice their opinion openly. They might lose fans.
Professional sports are very male dominated, and the last thing that a guy wants other people to think about him is that they are gay. This leads athletes having homophobic tendencies, and if there were an openly gay athlete the rest of the team members probably would not accept them. I think that in time this will change, but for now professional sports have a lot of homophobia.