Yeah I was also making the point to him about Henderson being fairly wide and Coutinho as a third midfielder to disprove the 4-2-2-2. It's such an interesting area about how you decide what formation a team plays and whether you base it on the defensive phase or whether you take it from average positions or whatever. Also shows how little a formation necessarily has an impact on a match.
Historically, it was easier to talk about formations because players stayed in fairly rigid zones (which is why man-to-man marking was so much easier to operate), if a team lined up in a W-M (3-2-2-3), they would maintain that shape in both attack and defence, and the game became more about 1v1 battles. Then teams started to change it, like the Hungarians, the Spurs Push and Run sides, then the Dutch and the Brazilians, etc. So the attacking phase became more about mobility and breaking the lines. At that point, it was easier to look at the formation in terms of the defensive positions, because attack-wise any of the attacking 5 or 6 players could move anywhere within a 40-50 yard radius, in any direction. So when we talk about formations, it's best to note the defensive shape more than the attacking one. You can also deduce the three lines in a three-line formation watching the game by seeing how many centre-forwards are left up front when the ball is in the defensive third, and how many defenders are kept back when the ball is in the attacking third. Then you just deduce the middle. That will give you at least a simple short-hand for what the formation was. The details after that can get a bit muddy though