Why has Marouane Chamakh become a flop in Arsenal?

I remembered when Marouane Chamakh was announced as an Arsenal player back in 2010, there was a feeling of anticipation and excitement as it was to herald a player coveted by many clubs after starring for Bordeaux and taking the French club to the quarterfinals of the 2009 Champions League. Here was a striker who could have provided us with a genuine Plan B. In the first couple of month following his move, he really looked like the real thing. In the first game, he got us a point at Anfield in the last minute. If I am not mistaken, he got something like 10 goals in a dozen games or so. However, we all know what happened next and how the Moroccan has fallen from grace, in both the eyes of the manager and the fans.
Many fans, including yours truly, have branded the Moroccan a flop. Yes, he definitely is a flop at Arsenal, no doubt about it. Howe...