However Rav Moshe Feinstein encouraged Bochurim to relax with sports, but to make Talmud Torah or something that helps Yishuv Haolam the Ikkur.
Perhaps Rav Moshe saw the Eis Lassos (time to act) otherwise Torah would be ‘hepiru torasecha’ (affected) if people had no leisure.
So in conclusion i think the more contact (hitting Derech Nitzchon) the sport is (e.g boxing) and the longer it is for, the more problems of Aveiro increasing you get.
So why should the Charedim that represent Torah report to other Charedim, encourage them all to do contact sports all day, (ok for the actual sportman it may be their Parnossa), but for Bnei Torah, or good Jews, should we make it a aim to get to this controversial Parnossa?