I was just a line handler in the Navy, never set the anchor. But my understanding is that the anchor is only a weight to guide the chain straight down, then they pile a bunch of chain on top, and that is what actually holds the ship in place. Each link weighs somewhere in the neighborhood of 350lbs each. Depending on weather conditions and the load of the ship will determine how many anchors and how much chain is needed to hold the ship in position. I remember at least one time we drug anchor in some bad weather and almost ran into our sister ship.
My assumption on this is that the brake men let it get away from them. Meaning they should have kept better control from the start and not let the brake overheat, thus taking away the stopping power, and going out of control.
One of the destroyers lost one their anchors outside of Hong Kong (I think) one year, they brought in a huge barge with a crane and some divers to get it back. If I remember it took a couple of days to recover all 12 shots and the anchor. (1 shot is 90 ft of chain. The chain is painted white every 90 feet, signifying each length, I was told that if you see red chain- RUN! Thats the end coming, and it whips around on deck before going overboard.)