But as Houston's Wade Phillips-led defense transitions to the 3-4 scheme, Williams has again become a building block.
Williams will move from defensive end to outside linebacker with the scheme switch, the Houston Chronicle has reported.
"I think he's the rush guy we need," Phillips said, according to the newspaper. "You have to put him in the spot that gives him the best chance to rush the passer all the time and be your star rusher."
Williams is encouraged by the move.
"I'm very excited about this," Williams said, according to the Chronicle. "I think it'll be a good change-up for our team -- not just for me, but overall because of the flexibility Wade will have with the way he'll be able to mix things up."
Williams has 48 sacks in five seasons, making the Pro Bowl in 2008 and 2009.
But the Texans, pegged by some in 2010 as a preseason Super Bowl contender, fired defensive coordinator Frank Bush after a 6-10 season, as Williams recorded a career-low 22 tackles amid injury problems.
He was placed on injured reserve in December with a groin injury.
"Playing defensive end, I have a few more responsibilities," Williams told the Chronicle. "Being an outside linebacker, I'm always on the edge. When the ball's snapped, it's full go after the quarterback."
Phillips compared Williams to Cowboys linebacker DeMarcus Ware, whom he coached for more than three years before Phillips was fired during the 2010 season.
"He's got the talent," Phillips said of Williams. "With him standing up, he lines up a little wider, and he's coming every time on a different angle. This gives him the chance to be the premier rusher, just like DeMarcus."