My memory is a little fuzzy on United in that period, but United used to generally dominate the game under LVG in terms of possession and overall chances, it just wasn't very exciting or inspiring football and he ultimately failed but the standards at United and Arsenal appear to be worlds apart. If Areta can achieve for Arsenal what LVG produced at United, they would likely give him a new contract.
Arsenal, when I've watched them this season, allow themselves to get dominated almost regardless of who the opponent is - it's no exaggeration to say Villa Leeds Wolves all played them off the park. They aren't good in possession, they don't create anything, they don't really stop the other team creating chances. They're not a physical team, so they can be quite easy to play against and they're now losing games at an alarming rate. They have a -2 goal difference and they have had random big defeat that skew the GD, like Liverpool and United for example.