Honestly I'd prefer it if we didn't bitch about the ref just yet. Let's just assume the man does his job well and focus on our team.
The best way to deal with the ref is to possess the ball. This is the way the game is going in all areas anyway. There is such a distinct advantage if you are constantly attacking. So many things can go wrong for the opposition. You can't make simple fouls anymore. Everything is a yellow or worse.
I don't think Barca could pull off that comeback even 10 years ago because PSG would have been able to slow them even fractionally by just kicking them. Instead of 6, they would give up 5 maybe.
If you choose to defend, there absolutely cannot be any space between the lines. Like Atletico or prime Mourinho teams. As soon as you allow a pass between the midfield and defence, the attacker is able to turn and run at the backline, something bad is going to happen for sure.