[Jim S]

During a series a team cannot change between types of balls (leather, rubber, etc.) even if they have been approved. Only at the start of a series. So you can't play with the rubber ball in the rain and then bring in the leather ball to kick to the oppenents.
We seldom have a team give us different types of balls to approve at the start of a game.
And, to tell the truth, as long as the ball they bring in is legal, I'm not too worried about whether I approved it before or not.