Lars Bender is epic DM. Got him pretty cheap in my Arsenal save, right off the bat 1st season, so not to sure how much he'll be second season.
Striker, gotta agree with everyone else with Chicarito. Out of favour at United and always seems to do me well in any save I manage to get him in.
I'd say you need a English Right-Back, kinda young and decent ability right away. Dont know who would fit that mould, but Sagna is getting old and you really need to look into getting him a replacement.
I'd say Szczesny. Played an Arsenal save myself and after 6/7 seasons he was the best 'keeper in the world. The eccentricity was a bit foul, he did make one or two costly mistakes, but saved me in so many games its hard to fault him really.
Another issue may be that your players have low concentration levels. Focusing training individually in these areas, especially defenders, would probably help. May even turn the tables around, and you could notice you are the ones scoring in the last few seconds