15% quality isn’t a that big of a difference in the game, there are factors in some way that can cause you to lose, did the 80% manager attend, all we the information we have is that you were 15% stronger, maybe he had a better formation than you as there is factors that “can” come into play.
Can we have photos or details of what went down in this match please?
I agree, some matches that you lose are totally ridiculous and can happen out of nowhere, and unfortunately when that scenario occurs, there is nothing you can do to stop it as the engine has made up its decision on who would win, this can happen anywhere from. 1-3 times a season, and those are the matches that there is nothing you can do about them.
However it should only happen to you no more than 3 times a season, absolute max 4 times in a season. Then as the others said, you are doing something wrong if you have more than that.