Arsene Wenger refused to single out individuals for criticism after Arsenal`s collectively poor performance was capitalised on by an impressive West Brom.
The Gunners were certainly off the pace at the Emirates, not helped by individual errors such as the one made by Manuel Almunia who let Gonzalo Jara's shot slip through his fingers for Albion`s second in their surprise 3-2 triumph.
But Wenger said: "Well, you can have question marks over many players if you look at the performance, especially defensively. Many players made massive mistakes defensively.
"I do not want to talk about any one performance, we were collectively poor. You could single out many players. Overall it was a poor team performance and we have to analyse why and respond well.
"It's unexplainable how flat the whole thing looked for the whole game, it's a mystery for me.
"In our performance something was not right. It was unusual to see a team as flat was we were."