The problem was the change in the writting staff
Season one was a very interesting season. Story was compelling, the characters, everything. Season two wasn't so good and season three was not worthing mentioning (it was incredibly bad).
I think the great problem is that the writers were not the same as in season one (s01 were the series creators, right?). This new crew simply didn't got the characters, they destroyed everything Roman, Peter and even Olivia were.