Jake, I think Primal should work exceedingly well for you. I'm many years removed from high school (football was my game). Since discovering Primal, I think back on the food patterns I had in school, and realize that most of my best games came when I ate primarily meat and veggies on game days. Unfortunately, my Mom prepared a lot of traditional Southern foods, so we normally had a lot of high carb and fried stuff most days.
I think you'll find your energy levels will be higher on primal, not lower. Your athletic program certainly should give you adequate exercise to maintain your strength and stamina. In your situation I think I'd start off by cutting out all breads and cereals (if you eat them). Stay with the sweet potato, no white ones. Try that for a while, see how it goes, then adjust. I don't think I'd do anything too dramatic to start with, go fairly easy into it and see how your body reacts. I would not worry about the calorie counts at all. To the best of your ability don't eat "by the clock"--eat when you are hungry. At 16, you are no doubt still growing, and you are very active, so your body needs plenty of good quality foods, feed it what it needs. The key is to stop eating when you are no longer hungry, don't eat until you are stuffed -- that path leads you to gaining weight whenever you retire your cleats -- like I did, + 5 to 10 lbs every year after football.