Many people are hesitant to join an established league because they fear they will be unable to compete with seasoned veterans, but many will be eager to join a new league forming in their area. Some will do it for the social aspects, and these are people who might seem less concerned with fitness. As is often the case, it might be their primary concern. Working out could be something they have failed at previously, and a friend or physician might have suggested they try something new.
Joining a group that is just being established gives people who need more exercise a sense of comfort, and they might feel they have a shot at fitting in with their teammates. While all of them are new to the sport, there is a sense of accomplishment in just joining up. As the season progresses, all of them will learn their limits and try to work harder. They will all find they have gotten more than just a workout than planned by the end of the season whether they win or lose.