See I don't think that's the case with Ferguson.
As I said, he'd already put teams out to play very disciplined games away in Europe in the early '80s using 4-5-1 and had, even at that stage, recognised the need to play a more possession based game rather than their normal high tempo style.
It's possible that his Aberdeen players were more tactically intelligent than the English players at Man Utd and he couldn't change style with them until he brought in some more foreign players who understood how to play a more controlled tempo, though.
could be but I doubt there had been much diff in the philosophy with which Scotish and English player were brought up at the time. Back then, while at Aberdeen, it's possible that SAF played that defensive scheme out of lack of quality players, especially the games in Europe vs quality opposition - same thing as the "parking the bus" tactics small teams use when they play big team ... they do it 'cause they don't have a choice ... it's not like Aberdeen at the time had super-talent in their ranks.
SAF may have talked about changing the way the Brits play football back then, but the first team he coached that exhibited such an approach, that I remember, was the ManU in the late 90's, which went on to win the CL eventually and even they were not entirely foreign to the good old British footie of long balls into the box and running all they long up and down the wings.
It's possible that he "forced" the ManU youth teams and coaches to change their ways and it took time for the generation of Giggs, Beckham and Scholes to eventually mature with a more modern perspective on the game.