I think there was an element of panic about that U21 game from the players themselves after the sending off, towards the end the players themselves bottled it for me, they didn't trust the system they were being asked to play, but lets face it few of them play it on a regular basis.
When City do it, we completely trust it, in pretty much every situation. A couple of games stood out for me last season. The Spurs home leg in the CL, if ever there was a game we were going to panic in, that was it, we didn't, we kept playing the way we knew worked, you can add Leicester to that, no panic just belief it would work. Only a genius can instil that belief into footballers, who lets face it are generally not the sharpest people.
I don't know what football was like in the 1930's, but Pep plays formations that appear to come from back then, all geared to attacking, a time when 100 league goals was not unusual for the champions, I don't know enough about those days to know if there was a similar genius way of playing, but I know I'll never see better than right now, perhaps someone my age thought similar in the 1930's, but there was a difference then, the whole league was closer, we even got relegated finishing only 16 points behind the champions (obviously 2 points per game then).