I appreciate what your saying but for me his skill set is too limited to allow him to be regarded as a quality player.
Yes he can drive the ball forward but he lacks the vision and /or the ability to see and implement the correct pass, instead he invariably opts for a sideways or backward pass thus squandering the advantage he has helped create.
I understand the idea of a defensive midfielder is to resist the opponent when he has the initiative but unless all midfielders are capable of not only winning the initiative but then exploiting it we run the risk of operating too often on the back foot. Which is why McCarthy ,and to a lesser extent Gana ,have their best games when we are playing superior sides.
I would prefer all our midfielders whether they are termed ‘defensive’ or otherwise to be able to play well offensively , or we waste a midfield place on what is really just a glorified defender which, in my opinion ,is what McCarthy really is.
I'm not quite sure how you reached that assessment on his quality mate. He is one of the few players in our team who has won a domestic medal and did so in adverse circumstances given the team he was playing for. He was also a part of the Everton team who scored a record Premier league points total and was one of the most pivotal players in that side. Im not sure our position is one where we can discard so easily players of that caliber.
The lad has horrible luck with injuries, but we are not innocent in that cocktail either, playing him when he clearly wasn't fit. Thus was his importance to the side at a point. The question is can he regain his fitness. Based on his performances when he returned last year, i think he can. If we were to sell him, now is the worst time to actually do that and poor judgement.
I dont actually class, McCarthy as a defensive midfield player the way i would look at Gueye as an anchor, he is box to box a true no 8, engine legs, and a good skill set offensively and defensively with a decent appreciation of holding possession, driving, increasing the tempo and pressing. We have midfilders who can do bits of the afore mentioned and in areas of that skill set better then McCarthy but not with the same range of all.
I think you are being idealistic to be honest mate and no offence intended, football is a balanced game, you need to earn the right to get and hold possession, win battles and impose yourself before you can look at creating, you need players with those skill sets and McCarthy is one. You will get no where playing two Gomes's or Artetas in central midfield. Its an area of the pitch that requires balance and you need to compensate for flair and creativity. For example you wouldnt play Gomes at 6 or Gana at 10.