1) The question you should be asking is what do I get out of defending a player? Essentially it's another form of trying to get power and control- but instead of targeting the player you are taking their side and trying to control the people making fun of them even though aside from them being on your team you have no personal stake in the matter. My point was I have been on the side of people that have been made fun of on an athletic stage and so I know what it's like to have that happen. The reality is if you are in this sport you are not going to make every fan happy every time even if you are Babe Ruth. Every player should understand that and understand that is something that they are going to have to deal with the further they go along. Essentially in my field it would be understanding the fact that I am going to have to deal with angry patients and family members from time to time and accepting that's the reality of what I face in my job every day.
2) My point is that people do things that they shouldn't but just because they do it doesn't mean that it's your place to correct them. Do you try to turn in everyone that is speeding? Do you try to intervene with everyone that is mean to their waiter? Do you try to stop people from calling our football players names on the Internet? You can't control what other people do but you can control yourself and when you try to call those people out what you are essentially doing is giving them control and attention- which is what they want- and it actually will probably have the opposite effect of what you are going for. Assuming your intentions are well placed and that you're not going for power yourself. So, by modeling not calling our players names and not highlighting those that do and giving them power you are actually doing more to achieve your desired effect than you are by trying to "force them to stop".