Correct.
In truth there was relatively little need to play 3-5-2 yesterday. We could have played 4-2-3-1 and got the same result.
People are acting like playing 4-2-3-1 is an 'open' formation. The fact its Jose Mourinho's default setting should be a sign its not.
We went to City in March, this year, playing 4-2-3-1 and won. That was possible because, as you point out, we were compact, sat relatively deep and used counter attacks.
There was no reason for Ole to instruct the team to try and press and play on the front foot. That is what created our issues, not the formation.
We played Liverpool 4-2-3-1 when we drew with them at Anfield and beat them in the FA Cup in January. Neither time did we look like getting pulverised. That's because, in those games, Ole was smart enough not to try and go toe-to-toe with them and to play on the break. Maybe he got giddy when we signed Ronaldo but, until yesterday, it felt like he'd forgotten that he's a counterattacking manager with a counterattacking squad.
Whether we stick with 3-5-2 or go back to 4-2-3-1, or 4-4-2 diamond or any of the other formations Ole's used, as long as we're compact when we lose the ball we should be fine most weeks.