I play this game for about four years and I personnaly think that formation and tactic for 1 match doesn't mean much. Even if the teams are equally strong. Means something, because you can not play some stupid formations or even worse tactic, but formation or tactic doesn't win the matches.
The only thing what win matches is the strenght of team. If you have strong team, you can play whatever you want. If you have weaker team, you are in trouble. By that, you can play the best formation ever seen on the planet Earth with the best tactic, you will win very rarely.
There is an algortithm who runs te game and there are some settings. First thing and the most important is the strenght of a team.
Now I expect that some guys will say here that this is not true, that they won some matches against stronger teams. Of course they won some, but how many times? A few.
When you look at the end of eveyr season, good teams are up and weaker teams are down. What does it say?
But again there is another BUT. Formation and tactic are very important for another thing. A good training with the right formation and tactic, give faster progress for your players. So, players must be well trained, you must chose te right formation for your team, not the best there is, but the best your team can play with the given players. With the good tactic, when they play at their best positions,
THEY PROGRESS FASTER. So, your team is getting better and better. But again, formation and tactic, does not win the matches.
That's my opinion. You do not have to agree, I respect everything what you have to say against this.