Hey there BeadyRoller I think the best way to see what's the issue with your tactic is to try and understand how your players are interacting with each other during a match. Usually people say that to create a very solid system you must start from the defence and build from there, but I tend to go against the flow and do the reverse especially with so much attacking talent as what you have at your disposal
Ok so a reason why your team did so well against PSG was probably mainly due to them being an attacking team like yours, meaning that every time your team foiled one of their attacks they became exposed to a counter attack from your team. The reason that doesn't work against a team like Wigan is like a poster already pointed they aren't going to have a go at you, their main objective against your team will be to stop you from scoring. That means that your attacking line will be overrun by their defence. Lets look at your 3 attacking midfielders, you will want them to create scoring chances and space for your striker whilst popping with a goal or two by themselves. But if you think about it, the way they are set 2 IF's and one AP the whole thing they will be doing is run into each others space since the IF's will look to cut inside into the area were the AP operates. That means that for a defensive team it is very easy to negate space for your creative players to do something, since they are all trying to use the central area of the opposition 18yard box.
So if I was in your shoes what I would be doing would be to find a way to solve that, simple giving your AP a support role would go a long a way to create more space for your IF's to work, but I would ask you to try turning one of your IF's into an advanced playmaker with attack duty. Hazard would do well like that I think, a advanced playmaker in that position works almost the same as an IF (even more so with the cuts inside ppm) but he wont be as zealous in his desire to make inside runs or attack the goal straight away, he will be a little deeper to receive the ball and then look to link with your other advanced players. The AP with support duty will be also a bit deeper forcing the defenders to move out of position if they want to close him down fast. That will open channels for your striker and IF to actually find space and put themselves into scoring opportunities. I would also recommend giving Falcao a CF role, quality strikers really tend to thrive with the freedom offered by that role. He will be generally making a nuisance of himself by dragging defenders away to mark him and getting on the end of the chances created by your 3 attacking players.
So that leaves us with the 2 CM's now, it is frequently pointed out that for this shape its more beneficial to move the cm's into the dm slot, don't worry into thinking that would make them focus overly too much into defensive duties and leave your attacking players isolated. That doesn't happen, a combination of either dlp def or dm sup would still leave your 2 cm's working pretty much as you have them now but they wont leave your defence so vulnerable, since they will sit a bit deeper when your team doesn't have the ball.
Another thing you also need to think about is width, since you have no wingers you have to rely on your fb's to provide it. Turning your fb's into WB sup will make them work pretty much like you have now but they will be a lot more honest with their defensive duties when you don't have the ball due to the lower mentality but since they are wingbacks they will look to attack like a fb att when your team has possession. Another thing that I find really helps me to create width is using the shouts Play Wider and Exploit the middle, it usually spreads my team making it harder for the opposition to overrun me but my midfield players still control the flow of the ball when I have possession.
This is of course just the opinions of a fellow player, they are by no means 'the right way' just what usually works for me.