If Morgan is dismissing United as being 'not big' , then what criteria is he using ...because other than Arsenal currently leading the PL, there's been diddly to indicate that his own team is anything 'big' using the same criteria he appears to be using for united.
It's can't be crowds (else united wouldnt be big), it can't be trophies (they are both lacking now - and if it's historical...ha!), so the only criteria Morgan is using is recency bias of this season (and at a stretch the past few of bottlers Arsenal being 2nd).
On any reasoned (which maybe the issue...) arguement, if he's saying united aren't 'big', he presumably is implying that arsenal are "'big'...which can only lead us to conclude that City are "massive" ;-)