Maybe someone can explain to me why wrestling 12 players (was it really 12, or was it 4, or was it 30, take your pick) in training is any different to tackling and then wrestling to the ground 12 players in a game? Except maybe they aren't opposition players that are trying to win a game, steaming at you at with a 10+ metre run up, with bumpers up, legs pumping and protection from the waist down (must avoid that hip drop) and protection from the tits up (must avoid that HIA charge).
Sounds to me like pretty standard fatigue training, repetition, keep going under duress, mental and physical hardening up.
Always a Bulldog