It´s because the result depends more on the game's decisions than yours and the gameplay is more and more random. So, having better players means nothing since you can´t get the best of them. That´s why also the market is down. Why would you expend coins buying an icon if Rashford, Lucas, Sissoko are similar or better than them? I´m not a good player and with a gold team, I´m facing really good squads and scoring with Giroud the same amount of goals than with Ibra Scream ( or more ). I notice myself that when I win those matches the game was clearly in my favor with rebounds, positioning, etc.