PITTSBURGH -- Forget brimming with confidence and projecting optimism coming off a 13-win season. The Pittsburgh Steelers' defensive players are still salty about that playoff loss to Jacksonville.

There's an unsettled feeling with this team early in camp, with each cliche assuming a deeper meaning. When defensive end Stephon Tuitt says the Steelers need to take it "one game at a time" and focus on themselves, there is no smile attached.

"Get back to our old ways," said Tuitt about his goal for the Steelers' once-menacing run stopping.

Added defensive end Cam Heyward: "Complete reset."

This team has more problems than when Le'Veon Bell reports. That Jacksonville-infused haze is real. The Steelers were genuinely shook by getting outplayed in every area by a team they were expected to beat. Every crack was exposed, with players embracing changes starting now.

Coach Mike Tomlin has promised a "challenging" camp, of which cornerback Joe Haden approved. He wants more physicality, and he even had a stat handy to validate that desire: The Steelers ranked 31st in missed tackles last year. Pro Football Focus ranked the Steelers second-to-last in tackle percentage on run plays (16.1 percent missed).

"There's no reason why we should be 31st," Haden said. "It's going to be a very physical camp. [Tomlin] wants to see who's going to be able to put people on the ground."

The famed "backs on backers" drill is coming -- when tailbacks must stop a full-speed linebacker off the edge -- but Haden wants more carryover.

"No blown coverages, nobody running free," said Haden, bemoaning too many instances of receivers running free due to missed communication.

To help offset those issues, the Steelers rebuilt the safety position this offseason by cutting Mike Mitchell, signing trusted veteran Morgan Burnett, drafting rangy athlete Terrell Edmunds in the first round and moving Sean Davis from strong to free safety. They know they can't replace Ryan Shazier at inside linebacker but signed free agent Jon Bostic to pair with Vince Williams and Tyler Matakevich.

But Heyward wants better cohesion at all 11 spots. Too many times last year the defensive line didn't know what the rest of the crew was doing, the team captain and All-Pro said, effectively botching good game plans from coaches.

No longer, thanks to less risk-taking or freelancing.

"When you lose, you learn lessons," Heyward said.

After a franchise-best 56 sacks last year, the development of young players such as T.J. Watt and an improving cornerback spot, the Steelers' defensive positives shouldn't be ignored.

Neither should the edge and desperation, which usually isn't so evident this early.

"For us to be able to say [we're great], we have to prove it," Tuitt said.