Mental strength innit. Winning every week, even against inferior teams, breeds momentum which carried them till February. Now they've started question themselves and it's all gone wrong. The beauty of it all is we were the ones who planted the seeds of their demise.
Plus in classical Redknapp fashion, he ground his best players to the ground right at the start with no regard for the final few months of the season and fucked up the Janurary window. Which is why he'll never be anything more than a midtable table manager.