Knit picking!
Point is that it takes playing well consistently on a week in week out basis to win a league, not just raising your game for the odd match like it does to win a cup tournament. Yeah, obviously every team has its bad days in a league campiagn but the point remains the same.
Why do you think that in competitions like the FA Cup the top teams dont always make it the furthest - its the nature of cup football that the best team on the day goes through - that doesn't necessarily mean that the best team goes through.