One opponent Paul O'Connell could not overcome

The IRFU at the time described it as “a suspected avulsion of the hamstring muscle from the ischial tuberosity”, but what is that in layman’s terms?
Medical sources contacted yesterday described the injury as tearing the common hamstring tendon directly off the bone— the ischial tuberosity, or ‘sit bones’. They added the injury is one which often happens when the player is in the ‘poach’ position— the player’s leg is straight but when he is driven back with force, the hamstring is pulled.