You may want to know that most people who post here are ex Jehovah's Witnesses. Their view on what is or should be acceptable may very well differ from what the Watchtower Corp. considers acceptable. That is not to say that some can't give you an explanation of what WT expects because many here are exceptionally competant at that.
One problem with this subject is that many people feel that Watchtower is often ambiguous so as to avoid being pinned own on certain issues (for whatever reason - legal or otherwise) and it may very well become a matter of interpretaion with issues like the one you have presented.
I have heard some discuss the concept of "competitve sports" being considered bad while I have also heard others comment on "contact sports" being bad.
My opinion is that any worldly association is considered bad by the JWs and therefor the acceptable standard would be whether or not the sport is involving group participation with non Jehovah's Witnesses. Since that is generally discouraged, I suggest that would be the standard by which a JW's conduct would be judged by their peers regarding the isssue of involvement in sports.
Perhaps there are some others posters here who can provide quotes from Watchtower Corp. publications which will discuss this topic.