I think there' are two separate arguments, because as a club, we've never had it so good, averaging 54,000 in a new stadium, whilst United implode.
Sure, we can argue about ticket allocation for the Old Trafford derby, but equally, there were complaints in 76-77 after receiving significantly higher allocations for both Old Trafford and Elland Road (FAC)
Simultaneously, the team arguably peaked last season, and for all sorts of reasons, has struggled to focus on the current issues. Sterling and Bernardo have both experienced strange dips in form, whilst David Silva in particular appears to have lost the competitive edge required for the top level.
We can't win the League every year, but people have the right to suggest that we should have performed better at Norwich or looked more focused at home to Wolves.