Hi footballmanagers.

I am a level 2 manager and today I had a game in the semi-finals of the champions league. My teams average quality is 20,1 and my opponents average quality was 18,5.
Plus, I had a 14% ball possession bonus.
Now I lost this game with 1-1(0-3p)
Now my question is what does the average quality actually mean? What was the main reason I lost this game?

Thankyou.