Why was heroes season 4 so bad? i am from the uk so no sneak peaks for anything please just your knowledge why?

it is like after their big triumph in season 1-2, they have lost it, and made it more like an emotional journey in 3-4 instead of the mysteries revealed combined with action packed scenes- like how flashforward season 1 is- what have they done to it and i hope flashforward season2 is not like this!!!