Manchester United have ben stumbling upon mistake after mistake for over a decade now whereas Chelsea had similar problems the past few years but seem to have found stability. If the owners were competent things would have been different. Emery has been brilliant at Aston Villa on a small budget and other clubs such as Brighton and Nottingham Forest have similar stories about new managers coming in and immediately making an impact (yet Manchester United have failed badly).
In all seriousness though, he has to go out LOL. United need an experienced manager if they want to be closer to the top four than the relegation zone.
I still think they have a few more Prem losses in them as long as he's managing though.