I know Arsenal currently has got a really good form but you cannot generalized the fact that they will be able to defeat any team now, they can likely meet Madrid in the champions league and except they have luck on their side, they are definitely not winning that game even in their best form with their key players present.
Arsenal is on a good form but doesn't mean they will win all the teams and besides there strength is only on this premier League and anything outside the premier League is out of there lead, which is why they can only be highly competitive on this premier league and not on the champions League because when they meet real Madrid they will no that champions League is indeed a game of champions, so we shouldn't expect anything from arsenal on the champions League because those leading teams will hardly give any younger club the opportunity to scale through the Quarters.
However another club I have so much petty on is Tottenham Hotspur it was as if what happened to them last season has totally broken all there wins that they are struggling to grow back, actually on there case I don't even understand if there management is to be blame or not because obviously they did not try for the club at all because my take on that matter was that before they emback on this season they should have sorted out the issue that made them to be playing that way because right now they are more bad than there previous season and they will face a shameful defeat against Arsenal tomorrow.