my opinion:
1. playing a sport- if it will bring him happiness and industry and esteem.
2. watching sports?- well, let him be the decider. One really should have some enthusiasm about some of the teams. Its called Western Culture and that is not against Torah. In fact, Torah supports Western Culture as I see G-ds message to our people. That said, too much viewing of anything is a real mistake. One should enjoy the spirit of sports and find that there is some sense of affiliation. So no problem here, just don’t watch more than say 1 sports event a week unless say it is football playoffs.
3. going to sports? Well if you can sport the price tag, go right ahead. Of course every child should I say be able to view a few sports events in his or her lifetime. I personally am almost 40 and have been to one football game, a few basketball games and maybe 7-8 baseball games. Oh yea, a few college football games too. But that said, these were expensive though very worthwhile experiences. But I personally am quite aggrieved by those who spend their every weekend or more at the stadium. That just does not seem to be our mission in my thoughts.