I think you hit the nail on the head, Smithy. In the early 70s, the all-conquering Leeds side had a team of choppers who could mix it with the best and the hardest in European football. In the late 70s, Shankley had a team of choppers who did the same and who inherited the Leeds mantle. Even Cloughie knew the importance of the "enforcer" role when he brought Dave Mackay into the side and won the league.
Fergie always played with an enforcer, plus a few across the park who were not afraid to get stuck in.
Without these kinds of players, teams are prey to the tippy-tappy football ****ery of Arsenal and Chavs, as United (under Moyes) is learning to its detriment.
'Pool haven't quite found the kinds of levels of out and out thuggery with which they muscled their way to glory in the 70s, but they have replaced it with a new kind of cheating, in the form of Sturridge and Goofy, who are overly prone to falling down, like they've been shot with a high-powered rifle, with the merest of touches.