I think we are all agreed on the Diego/4-3-1-2 saga, it was just a flat out disaster, with no decent full backs to support Diego, we sank. Picking Poulsen over Xabi Alonso has to rank as one of the biggest fuck ups in our history. Absolute absurd decision.
I just think overall Secco was the biggest mistake of the whole era. Like giving a toddler the keys to a Ferrari. He just had no a clue how to buy players.