I think you've misunderstood the 'rule' I am referring to - and that is that winning momentum - or at least consistency in an approach to games is a thing. The point Maccy was making - with which I agree - is that Saturday's game was not played with the level of professional, focussed approach that we should have shown with the PSG leg on the horizon. @ Letters - no I don't think that winning against Paris would have of itself meant a win on Tuesday night, but in my view we might well have gone into the CL Semi with a different mindset. People far more qualified to speak to these things say that the best performers in any sport focus on executing their game plan and maximizing their performance in each game, regardless of the opponent or the stage of the season.
I don't think we did this on Saturday. And I think that this lack of composure continued into the early part of Tuesday night's game. The performances against RM - also coming after draws - is no argument against this view. Nor is this an empirical argument that is won by citing historical results. For one, you can drop points without performing in as sub par a manner in which we did against Palace. I'm not really sure why the point I have made is so contentious.
And also @ Letters, I am also not saying that this 'momentum' (as a shorthand way of referring to the factors mentioned above) is the be all and end all, but I think we can all agree that at this level fine margins are important and Saturday was not good preparation for PSG.