Too true, not accounting for the fickle nature of people.
But regardless of how suprising Amauri's quick transistion may be, that he is a dynamic and very good striker was obvious, only questionable thing was not him as a player, but how he will score consistently or not etc. Being reluctant towards his signing, as some were, because we had good enough striker force (counting them being healthy, neither Trez or Iaquinta been that much), is understandable (or wanting better strikers if we are going to sign one, though too expensive they would be, me personally, I wanted Berbatov the magician, superior to Amauri, without any doubt).
Saying mediocre players like Borriello is better, is not something I even acknowledged for a second. Borriello who I think is good enough player, but doesnt belong in top team as a starter, was repetetive enough about that in XT regarding NT level regarding him

p
He works hard and would quite good prima punta to have around, in the Iaquinta role (and Milan misses him even if he didnt score), but no Amauri at all. His 19 goals season didnt deceive me, because it was essentially one great first half of the season, and totally off second of it (14 open play goals, last half of the season, he only scored pks, 5 in total, nothing awing, more of a Di Vaio scenario now).