And what you mention is something I already tested years ago-
"So Khris are you saying that it's better to train just 5 players in your team and leave the rest as 1* since those 5 will determine the outcome of each game?"
Basically you face a whole 7* team and a mix of 7*+1* and the scores will vary depending on the availability of the players provided by the rating variations.
So you can earn a 2-0 or a 0-2 perfectly.