We play a certain way which, at its best is very attractive, attacking and penetrative.
There are two reasons for me why this isn't achieved every game.
1) Players having an off day (see man utd result)
2) Injuries.
In both of these instances we need able deputies to our best 11. We don't have that.
You say that teams know that all our threat comes from wide areas, yet fail to acknowledge that we are missing Baines and were missing Coleman for a hefty chunk of the start of the season. Martinez looked to bring in Oviedo at left back, but he picked up an injury. He then picked Galloway who I think we can all agree, plays the game like a fearless CB at full back -full of endeavour, honest running, but lacks the fundamental skills that an attacking left back now needs in the modern game. I personally think that Martinez should be playing Mirrallas or Osman on the left i.e. someone who lacks a bit of defensive acumen but can either commit opposing full-backs (Mirrallas) or can execute something a little 'cuter' in the final third (Osman). Instead he has picked Naismith out there, I guess to protect Galloway. Again, I think this is wrong of Martinez and criticism of this selection is warranted in my opinion. But it's got nothing to do with central midfield.
On the other side of the pitch, Martinez has picked Browning and, then a combination of more attacking players ahead of him (and Coleman when he was fit). The right hand side of our play has looked impressive for the most part - whether it's been Deulofeu against WBA, or Kone vs Chelsea/Southampton. Again, I think Martinez made a mistake in picking Lennon against Utd. It was too-safe. But this isn't an issue with central midfield.
The point i'm making here is that team selection in the wide areas is causing us to look inconsistent, not in central midfield. Dropping Deulofeu, on the face of it, was very unlike Martinez as he has in the past played the younger players in the game after they made errors so their confidence isn't affected and they can put into practice what they learned from their previous game and mistake.
You make the statement of 'we needed another goal in the derby and didnt look like getting one", and by that you're suggesting a change of system? What about the fact that in the derby we were missing Coleman, Baines, Cleverley, Pienaar, Mirrallas. Players that we don't have the finances (another debate for another time) to have ready-made replacements for. Instead, the easy solution to some fans is "we should have dropped a holding player and thrown another man forward". It's not like we weren't putting Liverpool under pressure was it? We were missing some quality in the final third, in creating a goal threat. Whoever Martinez brings in will be giving the ball to these attacking players, not providing it himself.
You say that the midfield 2 don't offer protection I think they do, I'd throw your 'watch the games again" right back at you. Barry and McCarthy position themselves when we don't have the ball in the best place they can win it back. That might be not be sat on top of the 2 CB's, it might be trying to win the ball back higher, but their solely purpose is protection in these instances.