Originally Posted by juro
the thumb does not push the rod. Instead the butt of the rod presses against the inside of the forearm which forces the rod to bend more on the power stroke. It throws a very powerful cast and with a positive stop a very tight loop into wind.
One benefit of this backhanded type of cast is that it dramatically increases your backcasting power, which helps your forehand casting significantly when the wind turns around.
The other major benefit: locking the butt against your forearm will prevent you from getting tennis elbow if you spend a lot of time backcasting grain lines.