Nah. His achievements as a player are completely separate from those as a manager, untainted no matter how big a mess he makes from here on out, and beyond that I think he's done as well as you'd expect in the latter role as well. What he inherited here, wasn't the Manchester United of the Ferguson era, it was a ship taking in water on the verge of capsizing pretty much so even if he proves incapable of carrying us all the way to the top I still think he deserves a lot of credit for at least having steered us clear of that disaster.
And besides that: Come on, stop the negativity please or at least halt it for a few more weeks. We're nine points clear of the top with one game to go, and another thirty-one to go beyond that. The other contenders haven't started out great either, so there's no reason to consider this campaign a write-off yet and all this doom and gloom is way premature. A bad start to the league this season? Yeah, abysmal in fact by any standard considering the quality we now possess. But... We're only six games in, with the exception of two games we haven't looked anywhere near as hopeless as we did for the first half last year, and we've proven in the Champions League that we're a force to be reckoned with when our players just decide on it.
There's no reason to think this is anything more than your standard dip in form, the kind all teams go through every now and then. No reason at all, not yet anyways.