Everything about your post was hypothetical.
In my opinion Otamendi was getting beaten time and again, and was on a yellow. It maybe a subjective opinion, however a lot of other people also thought that Salah was causing City a lot of problems in the game's opening eg https://www.theguardian.com/footbal...er-city-liverpool-premier-league-match-report Mane's sending off was a pivotal moment which changed the pattern of play, and that was in part triggered by Ederson's bravery. That's not a hypothesis, it's a statement of fact.If Salah scored, if Mane hadn't been sent off, if Ederson wasn't brave. None of that actually happened.
Salah got away from Otamendi twice and done fuck all with it because we have a top class keeper.
Yet you conveniently leave out the fact that Mendy and KDB gave the young Liverpool full back a torrid time which resulted in us scoring a number of goals.
I don't like the system with 3 at the back when we're facing forwards like Mane, and Salah.