Lee Mason's refereeing was atrocious. Louis Saha was miles offside when Seamus Coleman launched his pass to him making him active. The linesman should have raised his flag there and then. End of story. However FIFA's rules are also clear when it comes to Koscielny's situation. An attacker will be penalized for playing the ball being in a previous offside position even if the shot or pass rebounds off an opponent and comes to him.
As many commentators have pointed out this rule prevents players from gaming the system by deliberately trying to get rebounds off goalkeepers or defenders to allow strikers to get onside. Even David Moyes stated that the goal should not have stood.
The aggrieved Koscielny had the last laugh as he headed Robin Van Persie's corner for a gritty comeback win. Another Everton lapse gifted an Andrey Arshavin's equalizer. Not the best display by the Gunners but they hung in tough.
Tim, that may have been the linesman's thinking too but there was no way one could interpret that as Kos deliberately trying to backpass to Szczesny. It was quite clear that he was aware of Saha but the ball accidentally rebounded off him. Many commentators have said that this would just lead to teams trying to exploit rebounds in similar fashion to keep strikers onside. Yes, Lee Mason did have an horrendous game. 8 yellow cards - 29 fouls called.
Interesting that Moyes thought it was offside too. My understanding is that because Koscielny made a deliberate attempt to play the ball, that nullifies the offside so the goal should have stood technically. If it had been an accidental rebound/deflection then Saha would have been offside. Of course, I would argue that Kos only played the ball in the first place because he knew Saha was there - an instinctive and understandable reaction for a defender.
Regardless, the fact is the goal stood but we won anyway.
For me, the biggest problem is the offside rule itself. There are so many nuances, and even players and managers don;t fully understand it. The job of the officials is hard enough as it is without having to interpret all these grey areas.
Having said that, Lee Mason had a stinker. He lost control of the game early on by not punishing overly physical play with yellow cards, and for constantly refusing to play advantage. Useless.
http://thearmchairsportsfan.com/2011/02/01/arsenal-comeback-keeps-them-in-the-title-hunt/