Stanley, 27, announced he will be out for the remainder of the season after the Ravens placed him on injured reserve. He will undergo surgery Tuesday, according to a source.
"At this point in time, my ankle isn't where it should be," Stanley said in a statement. "This is the best decision not only for my health, but also for the team long-term. I look forward to supporting my team from the sideline this season and coming back fully healthy in 2022."
This is the latest blow for Baltimore, which now has an NFL-leading 17 players on injured reserve. The Ravens had hoped Stanley would return fully healthy this season, which is why they traded Pro Bowl offensive tackle Orlando Brown to the Kansas City Chiefs before the draft.
Alejandro Villanueva, a six-year starter for the Pittsburgh Steelers, will continue to start at left tackle and protect Lamar Jackson's blind side for Baltimore, which has the AFC's best record at 5-1.
In another roster move, the Ravens promoted running back Le'Veon Bell from the practice squad to the 53-man roster. Baltimore had elevated him twice, so it couldn't elevate him again without adding him to the active roster.
Stanley, a first-team All-Pro and a Pro Bowl player in 2019, first injured his ankle two days after signing a five-year, $98.75 million extension. Last season, he missed the final 10 games after breaking his left ankle Nov. 1 against the Steelers. Pittsburgh linebacker T.J. Watt inadvertently rolled into the back of Stanley's lower left leg while trying to sack Jackson.
The NFL's second-highest-paid offensive tackle, Stanley underwent two surgeries on his ankle before this season. After being sidelined for the entire offseason and for the first nine days of training camp, he returned to play in the season opener in Las Vegas but visibly struggled. He hadn't played since. Stanley represents the third-biggest cap hit on the Ravens at $10 million.
The No. 6 pick of the 2016 draft, Stanley has been Baltimore's best left tackle since Hall of Fame lineman Jonathan Ogden.
"This is not what I wanted or expected when coming into the season," Stanley said. "Throughout the last year, I did everything I could to be 100% healthy so I could be out there playing for our team and city."
In addition to Stanley, Baltimore's other significant season-ending injuries are to cornerback Marcus Peters, running backs J.K. Dobbins, Gus Edwards and Justice Hill and linebacker L.J. Fort. They totaled 2,872 snaps in 2020.