Very disappointing to lose this game, because I'm convinced we could have gotten something from this game, if we had started we the right tactics and the right personel. It's especially disappointing because you can write the script for an Arsenal away game beforehand and you can outsmart Wenger every single time if you have the players to do it. (and we do!)
Arsenal was always likely to start guns blazing trying to overpower us when playing at home. If this is a given, then you adjust to it (like we used to do in the past) and soak the pressure by having a compact midfield and defence and then try to catch them on the break. We needed Schneiderlin in there to break up their play, because Schweinsteiger and Carrick were playing next to eachother and neither was breaking up the play and it ment there was a lot of space behind them which put the defence under pressure.
I my opinion it should have been one of Carrick or Schweinsteiger next to Schneiderlin in a compact midfield with little room for Arsenal's creative players to make moves. I was very concerned when I saw the line-up in midfield before the game. That midfield could potentially be fine when you're playing a smaller team that will park the bus, but not when you play a team like Arsenal away with creative players who will play through any midfield that doesn't offer enough protection.
If you keep the playing field small and don't give them space in the first 15-20 minutes, you can probably start taking over the control (read: possession) of the game and put them under pressure. That is if you haven't already taken advantage on the break in those first 20 minutes.
But none of that today. We started arrogantly with a wide-open midfield and Arsenal deservedly punished us for it and we lost the game in those first 20 minutes.
Darmian against Sanchez was also a bad idea, because Sanchez is too fast for him and he Darmian couldn't deal with that. Valencia is faster and would have been a better choice to cope with Sanchez. I admit I probably wouldn't have started with Valencia myself, but I would have subbed Darmian off (or put him on the left and sub Memphis off and move Young forward) before the first half was over, because he was clearly not going to cope with Sanchez. I don't know why he didn't do it sooner, because when you're 3-0 down after 20 mins and you can see clear problems like that, then you have to act immediately and not wait until the half-time. It could have potentially gotten worse than 3-0.
Memphis has been terrible really and hasn't done enough to merit a starting spot, so I'm glad he was taken off. Let him prove himself in sub appearances like anybody else.
In the end I think this game was a missed opportunity. With a different approach to the game, I'm confident we would have walked away with 1 or 3 points.