My question is, do we have any real data that changing formation is a bad thing?
no there isn't .
Actually many times used to change my formation twice a day without a problem.
When playing vs 4-4-2 ND, I set 3DC +1DMC
but if opponent playing with MR/AMR & ML/AML I use DR & DL.


I'd like to stay away from conspiracy theories, and concentrate on an honest discussion of tactics that go together well.
A myth saying that some times, a specific formation has the favor of the game machine (or the opposite)
http://forum.topeleven.com/formation...g-so-well.html
but I think it's only a myth.
I must add it in my Mythbusters thread if I didn't have it so far