With Mohamed Elneny's good form, one has to ask why it took until March for him to start a Premier League game. Did the extra three days after Swansea, a match that Arsenal lost, really make the difference? The question is pertinent because Arsenal have functioned somewhat as a team since Elneny has come into the side, a state of affairs that didn't exist in the matches leading up to his inclusion, perfectly encapsulated by the pathetic 3-2 loss to Manchester United.
While Arsenal have not been great since Elneny came into the side, they have looked more like a functioning side with the capability to win football matches. In that sense, Arsenal are back to where they were in the autumn; a side capable of perhaps going on a run of wins, but also one that can lose to lesser sides at home, with significant issues scoring. In this sense, Elneny has taken on the Santi Cazorla role, as being the player in the double pivot who offers some control, and offers himself to the centre backs to build play, rather than being a decoy, like Francis Coquelin. Elneny is, after all, a holding midfielder with a penchant for passing, whereas Arsenal's other available central midfielder (until very recently), Aaron Ramsey, is not; Ramsey has a penchant for passing, and his ability on the ball is strangely underrated by an increasingly louder minority of Arsenal fans on the Internet, but instructing him to play deeper and build play is to the detriment of what he offers in the attacking third. At one stage, Ramsey played very well in a holding role in 2013, and there's no doubt in my mind that he could do it if he had to, but Arsenal have different demands of him now.
The Ramsey-Coquelin midfield wasn't very good nor balanced, and Arsenal again found balance when Ramsey took up his auxiliary third central midfielder/right sided player role in the 2-2 draw at White Hart Lane. Alex Iwobi has taken on that role, with some slight re-jigging, since Ramsey's injury, and there's a reason why such balance is necessary. By playing Coquelin, a player who Arsenal try to actively ignore in the building phases, Arsenal's options in the middle of the park are limited. Thus, Özil has to come deeper, and the forward players become isolated. By playing either a player with the engine to play as both a central midfielder and a wider forward, Ramsey, or a wide playmaker, Iwobi.
Indeed, when Ramsey was playing as a central midfielder, Arsenal were effectively asking him to not only play as one of the two central midfielders, but also to continue the auxiliary role, making the third-man runs that Arsenal need higher up the pitch, while also passing and building play. Under such pressure, Ramsey's form declined. While playing Elneny, Arsenal are only asking him to help build and pass; but still, Arsenal are using two players, Elneny and Coquelin, for one role. The same was true when Santi Cazorla was in central midfield, and although Elneny's energy and ability to score from open play makes the situation slightly less dire, Arsenal are still highly flawed in the midfield.
This affects Arsenal most at home, while trying to break teams down. Away from home, Arsenal can play more on the break, and while the team has struggled to score at home, that has not been the case away from the Emirates, scoring the joint most goals in away games with Leicester. It is Arsenal's home record, the 5th best in the league (as opposed to the 3rd best away record) that has put them in a situation where winning the League is extremely difficult. When breaking teams down, every player has to be competent and skillful on the ball, and not actively not seeking the ball in the build-up. It seems necessary, then, for Elneny to be joined by Ramsey for home games when the latter is back from injury; Elneny is certainly capable enough to be the primary defensive midfielder, while questions of Ramsey's discipline are overblown to the extreme. Playing alongside Elneny gives Arsenal the best chance to recreate the Arteta-Ramsey midfield, a midfield that was extremely effective.
Long-term, though, if Arsenal are to be successful, then playing a pure destroyer is not the way forward. Mohamed Elneny's arrival has seen the team become competent again; for it to be good, a player in his mould must be given a prominent role as the #6.