My son graduates this year, and has balanced football, wrestling, and baseball all through high school. After his freshman season of wrestling, a coach said he had the potential to be a great wrestler if he concentrated on wrestling throughout the year. I tried to push him to do this, but luckily he resisted and I left it alone. He still wrestled in summer tournaments, only about 10 pounds heavier than during the season. The next year the football coach told me the same thing. I actually said that if they began telling the athletes which sports to play, they may not like which ones they choose. I think it is a little easier at the larger schools to concentrate on one sport through the year, but at the smaller schools, sometimes there are just not enough athletes to go around. He went on to have a great high school career in football and wrestling, and now has turned it on in baseball, and I am glad I was able to follow him around through all three sports.
On a side note, I have two boys, and they are two years apart. I bought an old wrestling mat from Craigslist and set up a small area in the basement. My boys go down there and beat the he** out of each other all through the year. Best $50 I ever spent....