The Steelers replaced Vince Williams with L.J. Fort out of necessity against Atlanta.

They did so by design against Cleveland.

"I feel like that had a lot to do with it," Fort said of the impact his fill-in performance against the Falcons had on the adjusted sub-package division of labor in last Sunday's 33-18 win over the Browns. "It built a lot of trust up in the coaches."

Head coach Mike Tomlin confirmed as much this week when he included Fort along with safety Morgan Burnett and nickel cornerback Mike Hilton when referencing under-publicized components of the defense.

The transformation began on Oct. 7 against Atlanta. Williams, normally the lone inside linebacker in the six-defensive backs sub-package the Steelers favor on third downs, was unavailable because of a hamstring injury.

Fort filled in and played 27 defensive snaps after having played his first 11 defensive snaps of the season on Sept. 30 against the Ravens.

The Steelers beat the Falcons, 41-17, and Fort finished with a sack and a fumble recovery for a touchdown.

Fort missed the Steelers' 28-21 win on Oct. 14 at Cincinnati (ankle), but when he was available again last Sunday against Cleveland, the coaching staff found a role for him.

It was the same one Fort had assumed against Atlanta.

And this time the defense posted season-low totals for first downs allowed (17), third-down conversions (3-for-13, 23 percent) and total net yards allowed (237).

Fort's contributions were perceived as more critical than coincidental in the immediate aftermath.

"He has really good ball skills," cornerback Joe Haden observed. "He's really good at dropping into zones, reading the eyes of the quarterback, he's very athletic.

"He's one of our most athletic linebackers in pass coverage."

Fort's return to the lineup against Cleveland didn't generate the same type of buzz as that of safety Morgan Burnett, who played for the first time since Sept. 16 against Kansas City.

Burnett played a linebacker-type role in the six-defensive backs sets, often entering the game along with Fort as Williams and fellow inside linebacker Jon Bostic exited.

"Those sub-package defenders don't get enough credit," Tomlin said. "They might not be classified as starters, but guys like Mike Hilton and Morgan Burnett and L.J. Fort are significant contributors to our effort.

"I'd be remiss if I didn't mention we had all three of those sub-package defenders available to us last week and that's probably why our third-down performance in particular looked the way it looked. We haven't had a lot of games this year where all three of those guys were available to us."

Fort still hasn't started a game in three seasons with the Steelers (his lone such assignment in the NFL was carried out with Cleveland in 2012).

But the chance to make an impact on defense is the next best thing for one of the Steelers' special-teams stalwarts (punt, punt return, kickoff and kickoff return).

"That's what I've been striving for," Fort said. "It's definitely exciting to get out there and show what I can do now.

"I'm a capable linebacker. Whatever the coaches need of me I'll provide."