any chart than includes XG simply won't be anything like the true detail.Its all subjective.
however simply put, no two oppositions are the same. to compare what the team needs to do against them is as pointless as comparing sheep and goats.
You simply cannot say the press was "worse" in one game over the other purely on a set of numbers. you simply have to take into account the opposition reaction to the press and all that good stuff.
For example guiata kicked the ball out of play at least 6 times, straight out under the press, in contrast milan were shell shocked and we were encouraged higher press trying to knock it about at the back.
I agree with you. You have less pressing opportunities when the opposition don't have the ball. Therefore looking at just absolute numbers isn't the best way.
But those charts factor that in already because pressing / possession adjusted
However our efficiency was definitely worse when you look at the efficiency percentage - that's irrespective of the volume of presses.