Just because one rav has an opinion on sports doesn’t mean that his talmidim have to share it.
I (lehavdil, if you’d like) personally hate sports. It’s easy to catch me incredulously trying to figure out why my dad and sister follow football and enjoy it. But I accept that there is SOMETHING, even if I am incapable of understanding it or even find that something to be wrong for whatever reason.
With all due respect to these mechanchim, I find it hard to believe that the best way to get students to buy their opinion is to specifically NOT validate their students’ desires and interests. If my teacher told me to stop watching movies, I’d consider her words if she told me that there are problems with shemiras einayim or it was time I could use for other things. If she told me that it’s stupid to want to blow my time watching fake stuff, I’d know that she’s not thinking about how to help ME at all- she’s thinking of how to transmit HER personal opinion to anyone who would listen. She’s not even TRYING to understand why I might possibly want to watch stupid fake stuff, just applying her blanket philosophy to everyone without thought about their individual feelings.
The story about the soccer game simply uses soccer as a mashal and, in fact, validates the student’s love of the game, in fact in a way equating it to ameilus baTorah in a way that the student could appreciate. Calling a baseball game stupid may have been the practice of a rosh yeshiva who sincerely believed it (and honestly, I can’t blame him…) but it’s not a way to really take his talmidim and their individual personalities into account and it won’t really convince anyone who doesn’t want to be convinced.
Back to the original topic- I’ve been to about five baseball games (Mets) and a couple more basketball games (back when the Nets were in the Meadowlands) and I don’t think it’s a problem. My family probably wouldn’t consider going on chol hamoed, though. Like people said, it’s not really the spirit of yom tov.