For me the main problem of TS4 is that it's impossile to fail (mistake). Yeah, maybe you can mistake when you arrive late to a ball (no more than 7 errors in 3 set), but when you attack (risking a lot), you never mistake, EVEN ON PuRPOSE . The ball always goes in.
Mistakes are part of tennis, and if you can't fail, or its very difficult to do (or the mistakes are absolutely random) then I think the game has a problem. And think too that GTS2 will have the same problem