It's not random?
There IS consistency. My God, did you not see the screenshot? How much more consistent than that do you want?
**** tactics are not consistent. Good ones are, but even then things won't always go your way. ****, it happens IRL too.
It's a SIMULATION about FOOTBALL MANAGEMENT, not just tactics.
How can you learn?
1 - Starting line ups. I win a lot of my games before the kick off - picking the right players for the job. Pay attention to the likely match ups.
2 - Watch the games. Not Key highlights. Not even Extended. At the very least, Comprehensive. Pay attention to the players who find space in their team. Pay attention to the players who aren't in yours. Pay attention to the players you have who do find space and what options they have then. Pay attention to both D-Lines. Is yours too high; too low? Is theirs high and vulnerable to through balls? Deep, needing your forward players to pull them apart before a midfielder breaks through?
In short, there's a lot you can do, but watching the games and paying attention is so important. I've said it here and on SI - a lot of what I know came from just watching matches. I watched full matches and a lot of them. I didn't progress as fast as everyone else, but I learned to the point where I now understand tactics in general so I can get away with watching less.
----
I'm not saying "I'm great" and "everyone else is ****". I'm saying you're blaming the game when it isn't the game. I could probably beat them though. What I won't do is "make you a tactic", because that's stupid. I don't know your squad and their attributes. I don't know how you've handled them through team talks and press conferences up to now. I don't know the United line up, formation or anything else about them. You want me to just randomly give you a "super" tactic? Not gonna happen. There's a downloads section for **** like that.
Also, I'm not sure you well you're doing but United are a good team. They're at home. They will be strong. Why are you so hung up on winning? Take whatever happens and move on. Even a draw is a good result. If you lose though, so what?
Tell you what - if you post the PKM and screenshot of the tactic for the match (or matches), I'll (or anyone else) can take a look and analyse it for you.
Even better, if you upload the save, I can take a look directly at the situation you're facing right before the United game.