Glad to help. Based on my experience in sports shooting, if your goal is to shoot action and fill the frame (either in camera or with cropping)a reliable guideline for lens coverage is as follows (assuming a 1.5 or 1.6 crop camera body):
200mm is good for about 25-30 yards
300mm is good for about 40-45 yards
400mm is good for about 50-60 yards
Beyond those ranges you really are taking a crap shoot that focus will be accurate and that you'll have enough detail in the photo to crop down and fill the frame. It's why football fields especially make it difficult to take photos from the stands because the stands sweep back - and the stands end about 15 yards or more from the field in most places. Baseball stadiums tend to go more up and stands are closer to the field of play.