Shaw, Rafael, Herrera, Carrick and Van Persie are all first choice team quality and most of the rest are good enough for second choice. This fully fit Manchester United team isn't worse than Everton lol and it's debatable about some of the other teams that finished above them last year. United have bought well now, it's just typical luck that of the signings they've made they've all got injured and EVERY game they've played so far this season at least one player has gone off injured, it's a joke.
You talk about youth and bringing players through but none of the top Premier league teams have done better, City and Chelsea play significantly less youth players than United and don't have a single one as good as Januzaj. Liverpool only have Sterling and Arsenal a handful that aren't anything special.
When you're forced to mainly play 3rd and 4th choice defenders with a midfield of 4th and 5th choice players it tends to lead to shit defending