I'll agree with that, but possibly not in the way you meant it.
No, it isn't at all. It's obvious that the change of manager has not yielded a good outcome in terms of how we've played in the first 5 months. BUt there are two things we don't know:
a) Whether anybody else would have done better - It's been said a million times that it was only SAF's influence that won us the title, and the players aren't as good as the top three's. So what makes everybody convinced that a different manager would have just dropped in and got us playing well within 5 months? The obvious point is that we should have bought in the summer, but it's not like we didn't try - our failure seems as much down to Woodward and the money-men as the manager, who did his part in identifying targets.
b) How things will go in the longer term. 5 months just isn't long enough to know what a Moyes United team looks like. Fergie's early yers are well documented, and somebody mentioned that Wenger lost 7 matches by xmas in his first season. Making a judgment on this short a period is just massively flawed. You can say that you can judged by the style of football we are playing, but clearly Moyes isn't sending them out with instructions to play shit, boring, incompetent football - for one reason or another, his plans just aren't being executed at the moment.
This isn't to say that things are guaranteed to turn round... we may find that in another year they still aren't executing his plans, or they are but his plans aren't yielding results. And at some point there does come the time to decide it's not working. But it isn't after 5 months, with only one new player, as a reaction to three matches when our two best strikers are injured.