I think Arsenal have had their slump (not sure what else you call DDLWL - 5 points from a possible 15 in the last 5 games).
After the Everton game, Arsenal have easy fixtures (West Ham, Hull, Newcastle, West Brom and Norwich - most of whom have little left to play for too since they mostly look safe from relegation) so Arsenal's form will pick up again.
Everton on the other hand have to play Man City, Man Utd, Southampton (away) and a couple of relegation battlers. The form of 5 wins in a row won't last.
Unless Everton beat Arsenal next weekend, I don't see them catching up/overtaking for 4th.