or your only sport is something such as martial arts, sailing, fencing, pistol / rifle, archery, etc. -- USNA will likely look much more closely at your CFA. They want to make sure you can handle the rigors of PS as well as stay motivated enough to pass the PRT every year.
[BTW, don't want to start a debate on how demanding the above-mentioned sports are. They are all great sports and require a high level of skill, dedication, etc. However, they generally don't routinely require the same activities as the CFA, PRT and PS (e.g., lots of running), which is what is key for SAs.]