"There's a little chip you've got to have on your shoulder," said Williams, who played four seasons with the Miami Dolphins before catching on with the Chiefs this year. "There's a little something extra you've got to have."
The Chiefs have needed that something extra of late from Williams, who has helped keep their season from falling apart after they lost their top two backs. Since the Chiefs started to call on Williams frequently in the last four games he has rushed for 204 yards.
That's not a ton, but he's running for 5.7 yards per carry and also has 19 catches and five touchdowns. During Sunday night's loss to the Seattle Seahawks, Williams had 13 carries for 113 yards and seven catches for 37 yards and a touchdown, though he also had a costly fumble.
Those numbers don't make up for the loss of Kareem Hunt, who was released a month ago after video surfaced of him shoving and kicking a woman.
Hunt had 14 touchdowns in 11 games. Without him, the Chiefs don't have a back who has as much big-play ability or can line up in a variety of spots and be effective.
But Williams is the closest thing the Chiefs have to Hunt. His production has been essential for a team that hasn't had its other top back, Spencer Ware, for two games because of injuries. The Chiefs in recent weeks are also getting less from wide receivers Tyreek Hill (17 catches and zero touchdowns in the last four games) and Sammy Watkins (hasn't played in four games because of injuries) and tight end Travis Kelce (one touchdown in the last three games).
"I knew he had this in him ever since training camp," quarterback Patrick Mahomes said. "You could see the talent. You could see the ability to catch out of the backfield but at the same time run in between the tackles. He's stepped up these last few weeks."
The Chiefs signed Williams as a free agent during the offseason because they wanted more running back depth. Ware missed all of last season because of a knee injury and the Chiefs were concerned about his availability for the season.
The Chiefs liked Williams' versatility, particularly his ability as a receiver.
"Not only can he catch the ball but he can pick up the blitz and we also know what's going to take place when he carries the ball between the tackles," offensive coordinator Eric Bieniemy said.
"Damien is who we thought he was when we saw him on tape. One thing we have been talking about all season long, you never know when your number is going to be called, so it is important that you are ready. I thought he did a heck of a job stepping up and making the most of that opportunity."
But Williams was a spare part until recently. He didn't play a lot during his four seasons for the Dolphins, starting just four games. He never had more than 181 rushing yards in a season. The Chiefs were hopeful but unsure how he would do in a featured back role.
"I thought we'd get a pretty good performance out of him and good effort," coach Andy Reid said. "It probably was even a step above that.
"That kid has done a real good job. We weren't quite sure what to expect. He just loves to play."
His limited playing time in Miami, plus the humble beginnings to his NFL career, allow Williams to appreciate the opportunity he has with the Chiefs.
"Just running hard," Williams said of his running style. "Just being consistent with that. A lot of guys aren't consistent with running hard. You have to find a way to do it for four quarters.
"Me being the person I am, I'm a fighter. Any chance I get I'm fighting. Every chance I get to get the ball in the end zone, I'm getting it in there."