Not a Man U fan, but yeah SAF was a genius who single handedly made shitty United teams win titles (basically his 2011 and 2013 titles both earned by teams with weak players and he even got 2011 to a CL final by not playing any good teams). Main reason fans question Moyes is that he cannot produce similar results, so then they look for reasons why he isn't doing well and it's like 'oh moyes isn't playing kagawa, we need kagawa' and it isn't like SAF played Kagawa that much either, but you get these types of questions from fans when you drop a lot of points the season after your team won the title. Also Moyes really isn't as credentialed as people like to think, imo, he did amazing work at Everton, but if you look at who United could have brought in, they have more credentials (trophies) than Moyes: Ancelotti, Benitez, Mourinho, Pellegrini, Redknapp, Di Matteo. Yeah Moyes may be a great manager for a mid-sized club like Everton, keeping them out of relegation, (and this is hypocritical as an arsenal fan who supports wenger) but wouldn't you want someone who had experience winning trophies at a big club, or any club?]
Anyway, I never thought Moyes was a good choice, yeah he is a British dude who looks good for the brand I guess, other than that it makes no sense to me. Also he is a massive idiot who fired a bunch of SAF's staff to bring in staff from everton, in case anyone has forgotten. Moyes is definitely deserving of much blame, not for the results, but for not really approaching this transition in a realistic way.