in 26 games this season, our defenders have been nothing short of superb. in 3 games, they let it all go. it's because they are put in situations where mistakes will be committed, by being unprotected against the most lethal sharpshooters in the league.
i actually doubt Wenger knows much about adjusting to other teams' tactics. he can coach a great system, but he's not going to be like Benitez who has 8 different defensive formations he can apply depending on the situation. Wenger's probably the best coach in terms of preparing a system, but lags his peers in terms of adjusting to opponenets