Perhaps it's a sign of confidence in second-year linebacker Vince Williams.
Ex-Bills linebacker Arthur Moats was signed by the Steelers Monday, but not, as written by Steelers Digest editor Bob Labriola wrote, as an inside linebacker. Labriola referred to the fifth-year pro as a "back-up outside linebacker with core special teams guy who can also play inside linebacker."
Moats played both outside and inside linebacker while in Buffalo, and in the scheme-diverse Bills's defense, even rushed the passer as a defensive end (his collegiate position). If his end-all position in Pittsburgh is as a back-up outside linebacker, the Steelers appear to have added the veteran they usually have at the position, and possibly ended talks about bringing back ex-Steelers and Bengals OLB James Harrison.
Or perhaps begin talks about the depth at their inside linebacker position. There's veteran Lawrence Timmons, and then there's the rest. Vince Williams, the default starter in 2013 after the injury of Larry Foote, is the only player the Steelers have with more than a spattering of plays under his belt. Also in there is Sean Spence, who hasn't played a down at the pro level, and Terence Garvin, who appears more of a sub package utility player.
That's a long way of saying Williams can likely be placed in as the starter opposite Timmons, as the Steelers have a little under $2 million in cap space remaining. Barring another contract move, the team probably wouldn't be able to afford a starting caliber player at the position. Not that anything can be ruled out this offseason in Pittsburgh.