I support Arsenal, IMO he's bad for Arsenal these days...he's incapable of building a team able to be successful.
There's always some sort of achilles heel, be it a bad defence, an inability to finish, mental fragility or injuries. He's not built one team capable of winning trophies since 2005, some say he has, I disagree (proofs in the pudding as they say) as everyone of his teams has been average at the back and success isn't achieved with a error prone defence.
It's not just about signings a team full of good players, you need players that gel together and make a great team, you also need to change tactics/formations according to what's put in front of you and you need to be able to react and make changes (and make sure you have some available) when things aren't going your way.
He fails miserably in many of these aspects, so IMO he needs to go then we can at last move on and look forward to a better future.
The players must shoulder some of the blame of course, but if you look at the truly great managers like Ferguson and Mourinho they make sure they players are motivated, hungry and work for the cause...if a player doesn't fit they sell him and find someone else. Whilst it's great to have players who are motivated/leaders and hungry it's more often than not, not the case...the motivation largely comes from the manager....I cite Mourinho again here and effect he instantly has on players when he moved to a new club...he makes them hungrier.
So IMO it's the manager that has to take much of the blame, he's the one that gets most of the praise when we win after all.