Yaya certainly cannot play in a midfield two when we play with two strikers. He naturally advances into the space behind Sterling and becomes exposed. But he was perfectly fine at the start of the season when we were playing 4231. We need to revert back to that, with De Bruyne in the middle but deeper than where Sterling has played in the last two games. Sterling back out on the left where he is much better than De Bruyne at helping his full back. We had a very effective system at the start of the season, particularly in the away games. I really don't see why we should move away from that.