And the three-time All-Star point guard believes injuries and a different system are the reasons why.
"I was injured the first year (and needed season-ending right wrist surgery)," Williams said Monday, a day before the Nets host the Jazz at Barclays Center. "I've really had injuries while I've been with (the Nets) the whole time. And didn't have the talent around me that I did (with the Jazz).
"And that system (in Utah) was a great system for my style of play. I'm a system player, and I loved Coach (Jerry) Sloan's system. I loved the offense there. We could've been a really good team. We just weren't that good defensively as a group."
Williams, 28, made the playoffs in four of his 5½ seasons with the Jazz. In 2010, NBA general managers voted him the best point guard in the NBA. But his play has tailed off ever since he was dealt.
In 90 mostly injury-plagued games with the Nets, Williams is averaging 19.2 points and 9.2 assists, but shooting just 39.6 percent, 32 percent from 3-point range.
He has not appeared in a playoff game since May 10, 2010. Prior to the start of the season, no GM voted him as the best point guard in the league.
Williams signed a five-year, $98 million contract during the summer to remain with the Nets, and was surrounded with a ton of talent by general manager Billy King. But he is shooting a career-low 38.8 percent from the field and 29.9 percent from 3-point range. According to statistics obtained from basketball-reference.com, he's making just 33.3 percent of his jump shots and shooting 26.7 percent in the fourth quarter.
Williams has been dealing with a litany of minor injuries -- most notably a sprained right shooting wrist -- but hasn't used that as an excuse. He thrived playing a mostly pick-and-roll offense under Sloan in Utah, but hasn't while playing a mostly isolation-based/1-on-1 offense under coach Avery Johnson with the Nets.
"I grew up in high school, my coach wasn't one of those guys that would let us just throw out the ball and let us play," Williams said. "We were a system team. We had staple plays that we relied on. We were good at execution. In college (at Illinois), we ran the motion offense. A lot of cutting, a lot passing, a lot of screening, a lot of extra passes. I'm used to just movement. So I'm still trying to adjust. It's been an adjustment for me. But it's coming along."
Williams thinks that he can eventually make it work playing Johnson's system.
"I believe I can adapt to anything," he said. "We're still a young team. Things don't happen overnight. It's still just December. We're working on it."
The Jazz traded Williams to the Nets for promising power forward Derrick Favors, point guard Devin Harris, two first-round draft picks and $3 million because they feared Williams would leave once he became a free agent.
"I understand what they were doing," he said. "It was smart on their [part], because there was a possibility that I wouldn't have come back."
Williams didn't want to answer questions on what could've been, saying: "I never got a chance to play it out. It was a year and a half before I was going to be a free agent."
Williams is 0-2 facing his former team.
"To me, it's just another game," he said.
Johnson also believes Williams will be able to turn it on and get going. After all, there are still 59 games left.
"He had a really good practice today, really strong practice on both ends of the floor," Johnson said. "I'm sure he's going to look to carry that type of energy into the game. In Deron's case, no matter how he's playing, he just wants us to win, and that's what it's all about. He wants to be really efficient. He's another player that I am not worried about."
Mike Mazzeo is a regular contributor to ESPNNewYork.com.