A former undrafted free agent out of Army, Villanueva has spent the past seven years with the Pittsburgh Steelers. He has started all 80 possible regular-season games at left tackle over the past five seasons, earning Pro Bowl selections in 2017 and 2018.
The 32-year-old hasn't missed an offensive snap in any of the past three years, per Pro Football Reference.
The Ravens already have a franchise left tackle in Ronnie Stanley, who signed a five-year, $98.75 million extension last October. However, there could be an opening at right tackle with Orlando Brown Jr. requesting a trade in February.
Brown, who wants to play left tackle, has reportedly drawn interest from six teams that have had "ongoing conversations" with his camp as of mid-March, per Mike Garafolo of NFL Network.
Todd Karpovich of Sports Illustrated reported talks could "heat up" heading into the April 29 NFL draft.
Rapoport noted there were "moving parts" on the Ravens offensive line, which might signify Villanueva could be used as a replacement for Brown. The team also lost center Matt Skura to free agency before adding veteran guard Kevin Zeitler, likely causing some shuffling on the depth chart.
One challenge in signing Villanueva could be luring him away from a division rival.
The Ravens tried to add Steelers receiver JuJu Smith-Schuster this offseason and reportedly offered him more money before he re-signed with Pittsburgh, per Jason La Canfora of CBS Sports.
A deal for Villanueva would still be a boost for Baltimore and give the team more flexibility going into the draft.