Last year people were screaming for Dalembert to be dumped because he would "never" get it. Now he's one of the cornerstones for the franchise.
Dalembert's hardly a cornerstone of a franchise.
Louis Williams was a clueless gunner who would "never" be a point guard in this league. Now he is one of the brightest young prospects.
I don't think many people expressed strong opinions on Louis Williams because nobody had any real playing time to base that off of.
John Salmons was a bum who was lucky to be in the league. Now he's averaging 20 pts a game.
He's averaging 16. On a terrible team. And only because of injuries.
Salmons fell out of favor because his previous strengths (defense, setting people up) were lost because of his newfound fondness of isolation plays and 1-1 play, which surprisingly manifested itself in a contract year. I think most people saw inherent skill to be a solid player, but people began questioning his motives.
And, of course, the biggest fallacy of your post. Lumping everyone into generalizations and pretending everyone shared a general opinion.