I would only have two suggestions for you --
1) See if you can bump the shutter speed a little to freeze the action better - particularly in #3.
2) Even though you were sitting courtside, I'm guessing you still had to crop these a fair amount to isolate the players as well as you have. If you have a longer lens, use it. Not only will it give you more flexiblity while you are shooting, but also you won't have to crop as much off which may give you more flexiblity with print sizes, etc.
Great Job. The OKC Tennis Center is an awesome place to take pictures!!
TDF