Since early last week, Williams, who reached the 10,000-yard career rushing plateau in 2011, his only season in Baltimore, had been mulling the decision to walk away from the NFL (again) to explore other interests and focus on his foundation. The 34-year-old acknowledged he could change his mind.
Williams, who was entering the final year of a two-year deal, rushed for 444 yards and two touchdowns on 108 carries in the 2011 season. He rushed for 49 yards in two playoff games. He also served as a mentor to Pro Bowl running back Ray Rice and the team's other young backs.
"I was a big fan of Ricky before we were teammates, but being around him this year is the best thing that happened to me in my NFL career," Rice said in a statement. "As a young player, you need to be around a guy who knows what he is doing, and Ricky was tremendous to learn from."
Added Ravens head coach John Harbaugh in the statement: "Ricky, in his time here, made a valuable and lasting contribution. I especially enjoyed getting to know him as a person, and I have the utmost respect for him. ... We wish him all the best in his future endeavors."
With Williams retiring, a position of strength in 2011 is now even more uncertain entering 2012.
Rice is an unrestricted free agent and the team's top offseason priority. If a new deal can't be reached before March 5, the team will place the franchise tag on him. Anthony Allen was third on the depth chart in his rookie year. Matt Lawrence, who spent the season on injured reserve, is a restricted free agent. They also have Damien Berry, who was on the practice squad in 2011.
Cedric Benson, Cadillac Williams, Ryan Grant, Chester Taylor, and LaDainian Tomlinson are among the affordable veteran running backs who are expected to be unrestricted free agents, but the Ravens like the young backs they have.
After parting ways with Willis McGahee last summer, the Ravens signed Williams to a two-year, $2.5 million contract. At the time, Williams called it a "wonderful way for me to end my career."
And what a fascinating career it was.
He won the Heisman Trophy in his senior year at Texas. In 1999, the New Orleans Saints traded their entire draft to select him fifth overall. Hip-hop mogul Master P. and his "No Limit Sports" organization negotiated his controversial incentive-laden rookie deal with New Orleans. But after three solid seasons there, the Saints traded him to the Miami Dolphins for four draft picks.
In 2002, his first season in Miami, Williams was the NFL's leading rusher with 1,853 yards and a first-team All-Pro. Two years later, after testing positive for marijuana for at least the second time and being suspended for violating the NFL's substance-abuse policy, he stunned the NFL by retiring at 27.
A year later -- some of which was spent studying holistic medicine -- he returned to the NFL for the 2005 season. He was suspended again in 2006 and exiled to the Canadian Football League.
Williams was reinstated by NFL commissioner Roger Goodell in 2007 and was again productive for the Dolphins, especially in the 2009 season when he rushed for 1,121 and 11 touchdowns.
After the Dolphins finished 7-9 in 2010, Williams signed with the Ravens, who he felt gave him a chance to finally put his fingerprints on a Lombardi Trophy. They came up two wins shy.
"I have to thank coach Harbaugh and the Ravens organization for the opportunity they gave me this year," said Williams, who rushed for 10,009 yards and scored 74 total touchdowns in 11 NFL seasons. "I had so much fun and really appreciated the chance to finish on such a great note."
Last month, Williams told The Baltimore Sun that he planned to play out his contract with the Ravens if they wanted him to, though he admitted, "I'm definitely in the twilight of my career."
Less than three weeks later, in an interview with 560-WQAM in South Florida, Williams said on Tuesday that he first broached the possibility of retirement with Harbaugh last Monday.
"I don't know if he thought I was serious, but on the phone, he was very supportive," he said.
Williams said that after the Ravens' loss in the AFC championship game, he exchanged text messages with former NFL coach and Miami Dolphins executive Bill Parcells, who told Williams to not chase the Lombardi Trophy for too long "because you can contribute in other ways."
That message "shook" Williams. He said it also reaffirmed what he already knew: that he wanted to do other things with his life, including traveling the world and going back to school.
But as we've learned with Williams, anything is possible -- including one last title run in the NFL.
Asked by WQAM if there is a chance he'll return to the NFL, he said, "Well," then paused. "The easy answer is I've moved on. But the thing I've learned about myself is, who the hell knows?"