In the absence of Jack Wilshere, Arsenal seem at last to have found the right balance in the midfield, with Tomas Rosicky conducting affairs at the tip of the midfield while Mikel Arteta and Aaron Ramsey act both as double pivot for initiating offense and shield for the defense.
The reason for this balance is also why this system is beautiful.
Here, Arsene Wenger has abandoned the bridging midfield role, opting for more solidity at the base of the midfield. This is achieved by the shield provided by Arteta and Ramsey, who occupy the hole before the defense and take turns to push up to begin attacks or press for the ball.
A midfield so deployed would normally yield a different sort of problem.
It would shift "the hole" to the middle of the field—where the bridging midfielder (the box-to-box) normally operates—because the creative midfielder tends to sit closer to the attack (see: this article for a discussion on "the hole").
Wenger has solved the problem by having Rosicky collapse inward when Arsenal are biding their time in possession, when they need to press for the ball, when they must simply rearrange themselves in proper defensive formation when off the ball or when the offensive players seek to shed their markers.
When Rosicky reverts inside to offer balance in the midfield, Santi Cazorla—deployed structurally wide—collapses inward to take up the position vacated by Rosicky, while Nacho Monreal, the left full-back, pushes up to press either the winger or the full-back of the opposition.
But one other reason why this system has been effective is by being compact.
This is achieved by a relatively high defensive line, which in turn prompts the two midfield anchors to push further infield, thereby reducing the space in the center where "the hole" would open up.
While both Arteta and Ramsey have been more defensively aware than has been the case in past Arsenal systems, they have not been content to merely sit flat and close to the defense. Doing so would yield too much problem infield, where the lone advanced midfielder would be overpowered.
The fact that the system as a whole pushes forward and high from the back eliminates part of the problem as noted above.
The other solution lies in the fact that Arteta and Ramsey have been very astute in taking turns to push forward to eliminate the space in the center, while the other partner provides the buffer from behind.
When the system operates thusly from the back, pushing cautiously high, it allows Rosicky to advance forward. With Cazorla pushing up and inward while Monreal provides width on the flank, the system becomes a 2-3-4-1. The high number of bodies forward allows for different passing options and retention of possession.
The fluidity of the system is seen in the ability of the players to both switch position with ease and revert back quickly and effectively to their default positions in the system.
The first of the two points has made Gervinho rather slippery, since he doesn't stay put in just one flank. This also is true of Cazorla, whose license to roam causes problem for his markers. The second allows the team to recover when possession is lost.
This new balance in the Arsenal system is what Wenger and Steve Bould have toiled to achieve all season long. First, Abou Diaby was the best option in the midfield, but with him, Arsenal played with a bridge in the center.
With Wilshere, Arsenal have struggled to find balance in the midfield. This is so because Wilshere is the kind of player who needs a team built around him. I am not convinced that Wenger has found the balance with Wilshere.
For one, he hasn't been as structurally pragmatic as Rosicky has been in the last three matches and this causes problem in the middle for Arsenal.
One other problem Wenger will probably be looking to solve is how to reintegrate Lukas Podolski and Theo Walcott in the team. But as they say, when it is not broken, do not to try to fix it.
It might be best to start the next couple of matches with the current XI and having said players coming in as substitutes.
Then again, Wenger knows best.