The thing I'd ask, is would Wenger have taken this lot lower than the Europa League places? I think the answer is no. So all Emery has really done is match Wenger, he's not getting them playing better than the sum of their parts. As Nayim said, they have a good forward line and a sh1te defence (midfield I'd say can be decent, more so when Ramsey plays) so they average out to a Europa League level team imo.
Their season hinges on whether they win the Europa. If they do, then it's been a good season, if they don't then it's a par season. Emery will need more time to bring in his own players and get rid of some deadwood, but will he get the backing? Stan Kroenke seems to not really give a sh1t, just happy to have a London Premier League club that generates good match-day revenue and has that Premier League TV money and location keeping them a valuable asset. He doesn't seem to be looking for them to go up a level from what they are.