I can tell you a little about players, tactics and formations. In the 90's Norway had a brilliant coach named Egil "Drillo" Olsen. He played a very demanding system with focus on defending and counter-attacking on every possible occasion. He also picked players with very specific abilities. F.ex he placed a striker with exceptional arial ability as a winger, and a good long range passer at the opposite back position, so he could make long crosses. In midfeild he employed players with high stamina who mad lots of forward runs, to pick up the flick ons from the winger/forward. BUT he didn't always have those players available, but the system still worked, no matter who he placed in the system! The record speaks for itself: No home losses in qualifying games for a decade, beating nations like England, Netherlands, Poland, Germany, Czech rep., Italy, Spain and so on.
The point is, that he made a team of quite average players believe they could beat anyone if the players did the job they were asked to do. And no matter who he played, they did their job, even when they were played "out of position", and it worked.