Your friend could potentially be insane...there's actually more than one way he could be insane.
1. He could be delirious, i.e. he could have great grand delusions of grandeur. Specifically, he could imagine that the Red Sox are the greatest Major League Baseball team and that they should automatically win the World Series every year, regardless of the other teams.
2. He could have chronic selective hearing, only listening to the good things about the Red Sox, which are few and far between these days.
There are many other ways he could be insane, but he could also be realistic and a true Boston sports fan; he could have delusions of grandeur if he wanted, but when the playoffs roll around and his team isn't in there, he becomes Jack's complete lack of surprise.