It really doesn't. Was it you who was saying this a couple of months ago too? Wasn't even true then, and it definitely isn't now.
We had this argument about Utd last season (not two months ago) and (I think) I was proved right?
Basically you said their form wouldn't last (somewhere around game 20) on the basis that they weren't playing attractive football and De Gaea was keeping them in games. But they did continue that form and they did get 4th place. And De Gaea is still keeping them in games.
They had almost par form from game 9 to the end of the season, dropping only a few points from par. Not bad for a team playing terrible football. And this season look at the APLT before their crash. I will happily admit that crash is quite something else and I think that its due to either a) players just giving up playing lifeless football or b) the rest of the league working out their system.
I think the tactical system he was using was working absolutely fine whilst it lasted. It was simple Arsenal 1980s style. The reason people were moaning was it's just not typical United. And it is boring. But they were winning. Like a Mourinho side but using a different idea.