Flagstick

Have you ever noticed that the pro's, when they get a hole in one or chip in from around the green, always leave the flagstick in whilst retrieving their ball from the cup. Why? Is it some obscure rule of golf?

I knew the rule about the flagstick while putting on the green. Trouble is that on the rare occasion that i have chipped in, I can't get my hand in far enough to retrieve the ball. I wear an xl glove at the least cos my hands are so big.