Why does ea "give" other player advantage???

Ok, what the f is wrong with this hut??? First, you play and score and shots are going where you shoot them, defence is playing like they should, covering passing lines etc. But then suddenly, everything changes. Every * player misses his shots, no one is looking for room to pass to, defence guy stop after blue line and gives opponent easy goal?? Is this some kind of boost so every player can win time to time?? Makes the game imbossibly hard? This continues 5-10 games and then it changes back to "normal".