The Steelers are bringing in safety Mike Mitchell to be an impact player, and in more ways than one.

His personality — he's an aggressive hitter — meshes with the Steelers' identity, and he would seem to be a good fit for a defense that long employed Ryan Clark, a safety with a similar mindset.

But Mitchell's biggest contribution might be his ability to get to the quarterback, be disruptive when he does and get loose footballs bouncing into the Steelers' hands, a rare occurrence the past two seasons.

While Mitchell's $25 million, five-year deal is the most expensive for an unrestricted free agent during the Kevin Colbert era, it's a back-loaded and cap-friendly contract that guarantees him only $5.25 million.

And should the Steelers decide after two seasons they made a mistake in signing the former Oakland Raiders second-round pick, they'll face $3.8 million in dead money — about $10 million less than LaMarr Woodley had when he was cut Monday.

The Steelers, uncommonly busy on the signing front to date, locked up backup offensive lineman Cody Wallace with a three-year contract and long snapper Greg Warren with a one-year deal Wednesday. They also announced the re-signing of safety Will Allen, who reached a one-year agreement last week.

Warren, one of the Steelers' five most-tenured players, will be back for his 10th season.

Wallace's return makes it unlikely the Steelers will bring back Fernando Velasco, who is healing from a late-season Achilles injury. Velasco filled in well for 11 games after center Maurkice Pouncey injured a knee in the season opener.

Some of the Steelers' 20-plus free agents were on the move, too.

The Arizona Cardinals announced they signed running back Jonathan Dwyer to a one-year contract Wednesday night. The Cardinals lost former Steelers running back Rashard Mendenhall to retirement earlier this week.