Sports photography requires one to know 3 things, where to set up for getting the shot, which lens gives the best view of the shot, and the time delay of your camera. A knowledge of the time delay gives you an edge over the guy next to you that is shooting in multiple shot mode. If you have lots of opportunities to work with and only need one shot, go ahead and spray and pray. The trouble with that method is that a little timing errors, delays in writing, and the exposure itself, over rides the accuracy of your camera’s shutter button. That means that even if you know that you started the camera far enough in advance for the 3rd frame to be perfect, there is no way to reliably predict that the camera will expose that frame when you thought it would. Think it out, if you are shooting in a multiple frame mode, at best you are shooting 10 frames per second (30 frames per second if in high def video mode). That gives you a 10% chance of capturing the exact moment (33% for video) you want, and a 90% chance of missing it (67% for video). The odds of getting exactly what you are aiming for are not in your favor and are much worse when you reduce the frame repeat rate. Do you still want to spray and pray?
By shooting in single frame mode, you learn to adjust your own timing for the shutter delay inherent in your camera. When your own timing is honed to a high level, you will know when to hit the shutter for best results. You are no longer basing the timing of your exposure on the false assumption that the camera will be lucky. You are in effect creating your own luck.