I disagree. A key to a successful fantasy team is to have no allegiances to any particular team. While I'm a diehard Sox fan, I must not be afraid to start a good starter against the Sox offense, or players against the Sox pitching. And this is my first year playing so I'm trying to do the best I can. And I'd rather win in fantasy than to have my team win in real life since the fantasy success is much more contingent on my own doing.
Keep in mind, I'm a Jaguars fan so I'm used to selling out my own team for fantasy purposes.