Cancer and Great player are not mutually exclusive. Allen Iverson is a great player AND a cancer. Some have made the argument that Webber is, too.
Bibby was not noted as a loser, he was noted as a player who can't make his teammates better. Here's a news flash: he can't.
Anybody who noted Diaw as a failure after his second year in the league doesn't have any common sense. I remember a lot of people that called him soft (and he's still kind of soft) and somebody who didn't like to put in the work, but I don't know of anybody that called him a a failure after two years; not even Olowokandi was called a failure after two years.