The were times last season where Alex Song was infuriating. Having started to get forward more regularly, he sometimes left Arsenal's midfield exposed as Jack Wilshere got accustomed to his deeper role and Cesc Fabregas flirted in and out of the side. When all 3 were fit, though, Song saw his best return in goals, and cemented his place as one of Arsenal's key players; indeed, Arsenal won only one Premier League fixture without him, away at Blackpool. This season, Song has been excellent defensively, while retaining attacking qualities from last season. With the departure of Cesc Fabregas, Song has taken on more of a key role in Arsenal's midfield, especially on the creative side.
Fabregas' departure has seen Arsenal's midfield develop a greater fluidity. The formation is slowly starting to resemble the 4-2-3-1 of the last term, with Aaron Ramsey playing the number 10 role. However, the Welshman has not convinced so far, looking uncomfortable when pressed and preferring to stay deep, leaving Robin van Persie isolated at times. That has frustrated the Dutchman, who requires runners from the wings and midfield to take the place of a traditional partnership. These runners let Arsenal take advantage of van Persie's false 9 role, and allows for a greater fluidity in attack, something we've seen so far this season from the wide areas, with Ramsey reluctant to get forward. It was Song who took the initative to get closer to van Persie in the first half, before Ramsey became more dynamic in the second period, after instructions from van Persie and Wenger.
While Song remains the chief defensive midfielder, tying with Thomas Vermaelen and Kieran Gibbs for the most tackles and interceptions per game in the League (I'm ignoring Andre Santos' one Premiership game) and leading the team in tackles in the Champions League (discounting Frimpong's one start), the newfound fluidity in the midfield allows Song to provide more of an attacking thrust, with Arteta and Ramsey dropping deep. Song, so far, has flourished in this role, assisting for Gervinho, making a "hockey assist" for Ramsey and playing key passes for Walcott in particular, among others. He used his allowance to go forward to finish off Arsenal's 3rd, with a sweet finish after switching the ball onto his right foot. While Song was allowed to go forward last year, and did so to good affect, it did somewhat cost Arsenal defensively. Mikel Arteta, though, is a much better defensive player than Cesc Fabregas, and is capable of playing a deep role. Aaron Ramsey is also, like Jack Wilshere, solid defensively, giving Song a stronger base when he goes forward.
Arsenal's key problem heading into this season was to replace Cesc Fabregas. Like with the 2002 Oakland A's and Jason Giambi, it is impossible to replace Fabregas with one player; that player just isn't available right now. Instead, Arsenal must replace Fabregas in the aggregate: his ability to keep possession, his chance creation, intricacy, and range of passing. Arteta can replace Fabregas' range of passing and ability to keep possession, and with Arsenal adopting a somewhat more direct approach, his spread of play to wide areas will be important. The problem that Arsenal have faced against Newcastle, Liverpool and Spurs is that without Cesc Fabregas, they can't break down a side that cuts off their wide players. The quick tippy-tappy play around the box of seasons gone by occurs rarely now, because Arsenal lack the intricacy of Fabregas. That has been helped in other matches, though, by Song, who's passing has become more adventurous, as seen by his passing against Bolton this season and last, and by his improvement in throughballs per game, which have gone up from .2 to 1.
Without Alex Song, Arsenal's midfield loses some of the new found fluidity, as well as a key attacking force. While Francis Coquelin and Emmanuel Frimpong can replace him fairly well on the defensive side of things, neither yet have his passing ability. Coquelin's assured performances this campaign have shown that he perhaps replace Song's excellent on both sides of the ball, but, even more so than last year, when Arsenal won only one Premier League game without him, Arsenal rely on Alex Song. The "Cesc role" is no longer in existence because of the loss of Fabregas; without it, Alex Song may fulfill his true potential.