A defeat in the next game will be enough for me.  I can understand 'blips' in form, but this is now nearly halfway through the season so its clearly more than a blip.  This squad is good enough to be fighting for top 4, so the blame sits firmly with the manager.  If we were playing well but losing by the odd goal then I would say 'hang on in there', but we look clueless.
The worst thing and most worrying aspect is there appears to be very little fight in the players.  I had a few bones to pick with Moyes but his Everton teams always put in a shift and were disciplined.  I think Bobby frailties are there for all to see now.  Tactically he is all over the place at the moment to the point where there is no discipline in our shape.  Players are second guessing passes and movement, and the defence is shot in terms of confidence because Bobby's insists on building from the back at all times. If he changed it up now and again and had the goalkeeper distribute it quickly to Coleman or Baines rather than the usual pattern of move it to the CBs, to the DM, to the RB, to the CB, to the other CB blah blah.
And his team selections are becoming odd.  Barkley for instance is most effective running at players and giving little pass and gos, but he is lost on the wing and behind striker doesn't work because the play is behind him most of the time.  I'd have Besic, McCarthy and Barkley in the middle everyday of the week but he insists on rotating the life out of the centre midfield.  Don't get me started on set-pieces either.
Another aspect is we try and play through defences and more often than not attacks break down - and we wonder why Lukaku goes missing.  What happened to getting the ball behind the defence and picking a cross, which is what Lukaku thrives on.  Its just all wrong.