Back button focus essentially gives you the best of both single and continuous AF modes, at virtually the same time. All you need to do is have your camera constantly set in continuous AF mode. Simply press and release the back focus button to focus on a still subject (and recompose as desired) or press and hold to track movement, releasing only if your subject stops moving.
I’ve been shooting sports for a while now and one of the greatest challenges, especially when you first start out, is gear. I’m not saying gear makes the photographer, because it doesn’t, not by a long shot (pun intended), but lens reach is everything in sports and with long lenses come’s large dollars. Physics is still a thing and for some sports, such as Cricket, you must have a long lens, there’s just no way around it.