You are arguing against something you have invented yourself. I am not saying they are always right, I am saying if you take enough seasons (a large enough sample), the teams that are favoured at the start of the season will tend to do better than those that aren't.
If you think that isn't true then you shouldn't be 'man shouting at clouds' on ccmb because you could easily be a millionaire by now, you have found a goldmine..