I don't know about other states with comparable population as TN, but I'm a high school tennis coach and I see something that is hurting our athletic talent in all sports. Namely, private Christian Academies and, to a lesser extent, home schooling. I live in Chattanooga, and there are at least six private Christian Academies in our area (Notre Dame, Boyd Buchanon, Chattanooga Christian, Grace, Silverdale, Collegedale). All of these schools play in small districts-- some of them have to play up, but only Chattanooga Christian is even in 3A (for football).
All of those schools steal players from the traditional public schools in our area. I'm not talking illegally, either. Just middle class parents that want to send their kids to mostly white, Christian schools. They stay in the smaller districts and win lots of championships in lots of different sports, but those titles are pretty meaningless.
Red Bank, for instance was hovering around 1400-1500 students when I was there: it is now smaller than 800. Part of this has to do with a new school on Signal Mountain, but SM is essentially a small, white, affluent academy as well-- lets face it, if you can afford to live on the Mountain . . .
At any rate, the best athletes are not practicing every day with the best athletes. Again, I don't care what sport we're talking, this is the case. If all those PCA's would go away, you'd have much more competition in the public schools, we'd have more schools in the biggest classifications, and we'd have much better talent in Tennessee in all sports.