After a promising start, Arsenal have spent the last month in some kind of midtable-ish rut'; a win against West Ham, losses against Norwich, Schalke and Manchester United, wins against QPR and Spurs, and draws against Schalke, Fulham and Aston Villa. If you're very kind, you could say they're inconsistent; if you're more pessimistic, you could say that this form, which is like a midtable side, indicates the kind of level Arsenal are at now.
Yet, that discounts the genuine progress that was made at the beginning of the season, progress that made them, according to Vincent Kompany, "the best team we've played against this season", which includes, amongst others, Chelsea, Tottenham, Liverpool, and West Bromwich Albion; i.e., most of the other contenders for the 3rd and 4th place spots. That progress, though, came when Arsenal's midfield were able to control the game; Arsenal have been able to control possession in recent matches, but they haven't been able to control the tempo, or move the ball quickly. Mikel Arteta has been marked very effectively since the defeat against Manchester United; since then, Bryan Ruiz, Karim El Ahmadi, and others have tried to stop Arsenal by stopping Arteta. Against Aston Villa, Arsenal's most frequent pass combination was Per Mertesacker to Mikel Arteta, and then, with the same number, Arteta to Mertesacker, because the Spaniard was unable to play the ball forward. Olivier Giroud received the most amount of passes not from Santi Cazorla or Aaron Ramsey or Alex Oxlade-Chamberlain or Lukas Podolski, but from Per Mertesacker, all in a deep midfield position.
Adding to that, Santi Cazorla seems jaded and has been lacking in creative play in most of Arsenal's recent games, making Arsenal more susceptible to a pressing game. One way to break pressure, of course, is to physically push up Arsenal's midfield, which is done by driving from midfield through dynamic dribbling. Aaron Ramsey could do this, but doesn't always, which is why Arsenal so desperately missed Jack Wilshere and/or Abou Diaby on Saturday. That, though, is part of a bigger problem; Arsenal are even more hurt by a pressing game because they don't move the ball quickly enough, part of which is down to two of the midfield, Cazorla and Arteta, being tired having played almost every (or in Arteta's case, every) minute of Premier League and Champions League football.
Before Wilshere returned, Arsenal's midfield options were Ramsey and Coquelin; Coquelin is lacking in experience and inconsistent, and Ramsey can sometimes be inconsistent, though he is starting to return to somewhere near his best. Abou Diaby and Tomas Rosicky were options, yet Rosicky has been injured all season, and Diaby has played in just 5 Premier League games, in which one of them, Chelsea at home, he departed after 20 minutes. There's a paucity of options in midfield; in 6 out of Arsenal's 13 league games, neither Rosicky, Diaby or Wilshere have been available, leaving Arsenal with just four midfielders; one of whom, Coquelin, missed time with injury.
This is hardly a new problem, either, which is why it is astonishing how Arsenal have failed to deal with it, given how much they depend on the midfield to create chances. Last season, Arsenal, for large stretches of the campaign, depended on four midfielders, and they look to be doing the same this season, seemingly out of choice, having sold Alex Song and effectively replaced him with balsa wood's Abou Diaby. The reasoning behind that seems extremely odd, especially when Wenger admits that Diaby doesn't have the muscle strength to be a consistent first team player.
Because of this, Arsenal are suffering. Mikel Arteta's influence has waned because he is being isolated, Santi Cazorla isn't creating chances, and Arsenal have been effectively shut down in four games in the past 6 weeks: against Manchester United, Norwich, Schalke and Aston Villa, they've mustered 5 shots on target. When Wilshere has played, Arsenal's play has been better, because he brings a second deep passing option to Arteta, and has the creativity and ability to break from midfield that Arsenal have been missing. Wilshere, though, has just recently returned from longterm injury, and it would be foolish to rely on him for the entire season. Clearly, Arsenal will need to buy in January; but, in the meantime, they will need to find an alternative. It may not be easy; but Arsenal's success this season will depend on it.