I also didn't like the way he walked away, but don't you guys remember why he did?
He said he "wanted a chance to win". He felt that the ownership weren't making them competitors. In his book he says, "whenever a player became good, they would trade them instead of paying him".
Ironically, he was asking for a trade, or a way out of his contract. It was the ownership that said "No", and put his back against the wall, which in turn made him just walk away (feeling glad that he also has his health).