It's a fairly moot point though, because it's pretty rare to get odds of 1.8 on a team like United.
Take their next game - it's against Villa, 13th in the table and in poor form. They're around 9/1 to win.
United, correspondingly, are priced up at 1.36. If you wanted to take a team at odds of 1.8, you're looking at Chelsea away to Sunderland - Sunderland in good form, Chelsea with a habit of failing to win; City away at Birmingham - very tough game at St Andrews.
If you took the games where you could get 1.8 on United, it would probably be against Chelsea, Arsenal, Man City, and if United are at home maybe not even all of them. Perhaps some of the tougher away fixtures. And, correspondingly, they won't have a 60% probability of winning those games.