"Su pelota golpeando está excelente."
Your ball striking is excellent.
2 Answers
Sorry, Jack, but that won't work. Gerunds (striking) cannot be translated as "gerundios" (golpeando) in Spanish. It doesn't make sense; you have to use a noun, and if there is none available, you have to rephrase it.
Tu toque/golpe de pelota es excelente
Golepea la pelota muy bien = You strike the ball very well
"pelota" can't be used as an adjective and "golpeando" can't be used as a noun.
Perhaps: Golpeas muy bien la pelota. or Golpeas la pelota muy bien.