It's just more noticeable when Davies doesn't play well than the rest of the midfield (Gana, Schneiderlin, Sigurdsson).
Davies' game is about trying to move the ball forward whether that be in the form of a pass or running with the ball in the opposition half. When he's not playing well, that means he's giving the ball away or being dispossessed on the ball. He hasn't been playing well and it's noticeable because those sort of instances have happened.
Gana, whether he plays well or not, he'll be chasing players down and at least trying to win the ball so there's always going to be positives in his play even if it's just through sheer effort. It's hard to tell when Schneiderlin plays well or not because he hardly moves from the centre circle or makes a difficult pass, it's only when the whole team is a mess (See Arsenal away last year) that you notice his terribleness. If Sigurdsson has a poor game then it's just because he goes missing, similar to Schneiderlin that it's hard to lament a player when he doesn't do anything (obviously wrong) in a match.
I'm just hoping Andre Gomes has something about him or Dowell can provide us with a change because it's the biggest problem area at the moment.
Davies is off form to sure but definitely scapegoated because of the way he plays.