My Coach said the specifically said not to use a rosin bag and said that the puff ball will keep your hands dry I and that is a direct quote from her and don't ask me about punctuation cause I suck at that but she said to use the puff ball to keep your hands dry and out 90% out all the people in my winter league and summer league use them. I hardly see a rosin bag sometimes I see tape or patches but isn't that for keeping the thumb hole from rubbing too much even the ball is drilled right? I use a puff ball and it helps.