PITTSBURGH -- The Pittsburgh Steelers have restructured left tackle Alejandro Villanueva's contract to create close to $4 million in salary cap space for the new league year.

The Steelers will convert most of Villanueva's 2018 earnings, which includes a $3 million roster bonus, into signing bonuses. Villanueva signed a four-year, $24 million contract in July.

Since February, Pittsburgh has restructured four veteran contracts totaling more than $25 million in new cap space. That number will rise to more than $30 million with the imminent release of defensive backs Mike Mitchell and William Gay.

All this signals the Steelers are open for business starting this week, but that is only partially true. After all that work, the cap space isn't plentiful -- probably around $6 million to $7 million. The team gave restricted-free-agent tenders to kicker Chris Boswell ($2.9 million) and linebacker Anthony Chickillo ($1.9 million).

The Steelers are interested in signing an inside linebacker but usually don't spend much in free agency's first wave.