11% overall difference is nothing and is a very unreliable way to look at teams. To properly investigate a team you need to open their squad page and look at the individual players. You may find for example a player in the other team with an overall rating of only 85% but some of his individual (white) skills may be over 150% while some other (gray) skills may be only 10% making his overall rating the 85% that a lazy manager will see. Now multiply that through the whole team and that team you thought was 11% worse than yours is actually superior to yours and will most likely beat you.
So quit complaining about things you havent bothered to look at or try to understand.