Why David Moyes won't be a flop

Liverpool fan in peace.
I said this a few weeks back as a comment, but never really got my point across. I got a few decent responses, but I'd like to know what a few more United fans think.
I personally am a bit confused as to why so many people are upset/worried about Moyes. Okay I understand there are some trolls on twitter saying #MoyesOut after a friendly defeat, but there are some genuine doubters.
Let's start off by saying it will be impossible to replace Fergie. It's not even worth saying, no one will ever emulate what Fergie has done for Manchester United and for football as a whole.
However, that isn't to say that someone still can't come in and perform well. I see all these Liverpool/Chelsea fans etc. laughing at how united are fûcked, but they are far from it. Title winners don't transform into clueless lunatics in the space of one holiday.
You still have the likes of Rio, Vidic, Evra, Carrick, Rooney(?) and RVP. All are both established title winners and top, top players.
I think Moyes will need time to adjust to the task at hand. I can't see United winning the title next season, and I reckon you'll finish around 3rd if I'm truly honest. Id be surprised to see Moyes delivering a league title in his first year. However, the current winners you have will help carry the club until Moyes finds his feet and be able to move forward with United as one.
And to be fair, I'd rather you stayed at the top and not totally collapse. I would be disgusted if the Londoners were seen as the most dominant force in Engish Football. Liverpool will hopefully be back up there one day, and us 2 can finally have that rivalry that we've been waiting all these years to see
YNWA