Could be down to a change in our team structure. Last season Martinez favoured Pienaar and then Osman on the left flank with one of Mirallas or Deulofeu on the right. It worked quite simply, Baines would go on the overlap, Barry would drop into the back three, Barkley would come into the middle of the park, and Pienaar would drop infield providing cover for Barry and Baines and a passing outlet for both. On the other side McCarthy would drop in when Coleman went. That means when teams got it they had Barkley and Pienaar to run through before getting to Barry in the central area then the back two.
Now we are effectively playing two up front and two out and out wingers. So in the same scenario Baines goes, McGeady hangs out wide, Barry then has to cover left back, Naismith is making a run upfront and who is left manning the fort if we lose the ball? McCarthy, who has the entire middle of the pitch and right hand side to cover. Did I mention that Coleman's also bombed off in attack as well? This is why we are seeing so many goals come from that right hand side that was absolutely locked down with McCarthy and Coleman last season. We're seeing Hazard taking a run at McCarthy in the penalty area-an impossible situation for any holding midfielder to deal with.
In my opinion he was magnificent in the Arsenal game when our backline squeezed up (first 80 mins) and he could singlehandedly obliterate the space for their midfield. When our backline ridiculously dropped back it just allowed players like Ramsey Cazorla and Ozil 20 yards more space that McCarthy found impossible to cover, hence another two goals from the right side.
If we stick to this attacking formation we have to accept our defensive players will suffer. If Pienaar and Barkley come back in and we go back to 4231 rather than 424 we will see McCarthy back to his absolute best.