My grip is already pretty relaxed, so why does my wrist still hurt?

You may not be absorbing the pace properly and are keeping your wrist too rigid at impact. A relaxed grip reduces muscle tension, but if your wrist stays locked when returning fast drives or overhead smashes, more of the impact is transferred directly to the wrist joint. Without a slight give or controlled paddle movement to cushion the shot, repeated stress on the wrist tendons can still lead to overuse pain.