Good post Decentric. It shows another variation on the whole Popa world.
If you want find a post from someone I find it useful to click on their name/picture then you get to select Recent Activity.
As far as I have read, most people acknowledge that Popa has been a huge improvement on where Arnie had left us. If that was all the forum offered I would find it boring. It is the individual's focus on so many different parts that make it entertaining and educational reading. Where one person focuses on the absence of Nisbet, another focuses on the keeper and another on the defensive nature of the second half formation, and so on.
The selection of players is less about the merits of those chosen (who generally do get acknowledgement when they perform well) and more about the greater perceived potential of other individuals. It is rarely a black and white argument saying he should not have picked a particular player - it is suggesting that on form and perspective other players deserved the chance to be the one we are applauding selection of.
We could say "that is an unexpected selection - I will watch with interest how that develops in a game" or we can say "WTF is Popa doing - that player has obvious weaknesses and failings unlike this other player". The first sort of comment is not really worth discussing on a forum. The second brings in everyone's opinions on the player selected and the alternative offered.
We have to expect that people will criticise - few people post online to say that something was OK. There is little drive to do that. What we want to publish are the bits that we think are wrong, that in our own eyes and experience can be done better, and perhaps we will find validation for our thoughts and ideas. It is quite addictive to post your own thoughts (as Mono said a long time ago) and there is something in having both agreement and dispute when the other parties give reasons for their own perspective (as opposed to the old "Tard", "Loser", "You are" discussions we have seen in the past). In this forum the acceptance of your right to hold and voice your opinions are pretty safe. At the same time none of us will get away with a statement that someone else disagrees with unopposed.
The opinions we see on Popa's selections and tactics tend not to totally bag out everything about him. What they do focus on is the aspects that seem to clearly need improvement in each of our own diverse perspectives.
Against China we got a win by dominating constructively in the first half. We could have continued that way in the second half and kept the game out of China's hands, but Popa's mentality of "we have got this let's hold it" is open to much criticism - in my eyes especially because we have proven to be untrustworthy over time as a total defensive group when we try to shut up shop.
I doubt anyone believes our defence is rock solid (let me have it if anyone disagrees

). So why would we rely on that when we have better options to continue with the first half strategy? Especially when this was the last game in the window and saving legs is not a factor. We have 5 subs available these days so second half blockouts are nothing like they used to be. The opposition will simply bring on fresh legs to probe our structure until they break through. Popa is known for this protective strategy and it deserves criticism and discussion - but that does not also mean that the people arguing against his methods find him totally unworthy.
Most people support alternate player selections on the basis of how they have seen a player performing. It is a bit simplistic to think they are arguing their case purely because they are playing in a tougher league. No-one says "Bob is shite but he is shite at a great club so pick him". Club and league is a relevant factor in terms of opponent skill but the players people get behind first and foremost have proven themselves in some capacity with their play.
To use your Arnie example, I also have huge respect for him saying he lost it. But remember that many of us on this forum had been pointing that out and calling for change long before it got to that point with him. An example of where the perspective of the average unqualified punter could be argued to be more sound and to have greater decision making clarity than the qualified certificated manager. Over simplified for sure - but you get my point.
To my eyes, the 'general' consensus on this forum is that Popa has done great work compared to where we were, has gone a long way to restoring pride in the green and gold on field, and now we can look to the next stage of our development - beyond the failings that we experts argue back and forth.