If Petrie had waited and IF Webber had degenerated is moot. Petrie didn't wait and, BTW, Webber didn't degenerate. He adapted his game and actually put up pretty decent numbers in a totally different offensive scheme.
He was traded because of his salary, the potential for debillitating injury, and the offer from the 76ers - it wasn't like Petrie was trying to pull the wool over anyone's eyes.
The question was would he have made a difference in the playoffs.
Since he DIDN'T collapse in Philly and was able to perform for them post-season, there is every reason to believe he would have played even harder here - for the Kings. Is that so difficult for people to acknowledge?
And for the record? Doug Christie didn't have a history of injuries. His trade was primarily because of his salary on the books, too, along with his age, and declining production. (Which probably was related to the plantar fasciitis and bone spurs, which have now been removed.)
I don't mind the rebuilding but I fail to understand why some people have to justify the trades by belittling the players involved.