Seven years later, he's fighting to get back into the league after a number of drug-related incidents tarnished his reputation.
"I'd be lying if I said I did," said Williams on Monday after practice with the Lakers. "I've been through so much. I've been to the bottom of the bottom. You've just got to keep your head down and get through it."
"Sometimes he gets left out in the cold because he shouldn't have done what he did," said D'Antoni. "If you know his character, you know what you can get."
Williams was first arrested in 2007 on a marijuana charge. In 2010, he pleaded guilty to a separate, misdemeanor drug possession charge. In 2012, Williams was arrested in yet another drug incident.
D'Antoni liked the 6-foot-9 Williams as a mobile power forward with shooting range. He was willing to go to bat for Williams this summer.
"I knew that Shawne, if he gets focused, he can play," said D'Antoni. "He's got a huge amount of talent."
"You've got to know the guy's heart. He's got a good heart. He's very respectful," he continued. "Sometimes he's gets unfocused ... maybe in the wrong environment, but overall I know he's a good, good guy."
Williams, who signed a one-year deal with the Lakers at the minimum $916,099, has $100,000 of his contract guaranteed.
On Sunday, Williams started at power forward for the Lakers in a 97-88 loss to the Denver Nuggets.
"I've been a fan of his for a long time. I think he spreads the floor. He battles," said D'Antoni. "[He's] not a great rebounder. He's a very good three-point shooter, he's in the 40s. He doesn't put the ball on the floor, but I don't want him to. I just think he lets everybody around him play better."
Williams' spot in the starting lineup may not be a fluke -- D'Antoni is considering making that a regular role.
"That's possible," said the Lakers coach. "That's why we're going to do the next 30 days and players will tell me which way it should go."
"[Williams] would be first in line right now," he said. "Hopefully we'll get Ryan Kelly back. He's another guy who can stretch the floor."
Kelly is almost ready to start practicing in full with the team after rehabbing a foot injury since April.
Williams is happy to do whatever is asked of him.
"I'm happy to have any role. Just to be around," he said, "I don't care if I don't play."