"Going into Spring Training, I was 99 percent sure that I would retire at the end of the season," Washburn said during a telephone interview. "I was ready to be done."
Washburn, eligible for free agency for the second time in his career, isn't sure where he will pitch next season, but said, "Seattle definitely is toward the top of my list. I'll just have to see what happens when the free-agent season begins."
A player must file for free agency within 15 days after the final game of the World Series. The Tigers, who acquired Washburn on July 31, have exclusive negotiating rights during that 15-day period regardless of when the player files for free agency. Detroit, however, is not expected to retain the lefty.
It will take time to establish the latest free-agent market, and the 35-year-old Washburn realizes it could be a much different journey for him this time than in 2005, when he accepted a four-year, $37.5 million offer from the Mariners on Dec. 19.
But he said the length of a new deal isn't as important this go-around.
"I don't want to play four more years," Washburn said.
Mariners general manager Jack Zduriencik keeps his offseason game plan to himself and his closest associates, so it's not known whether the organization has any interest in bringing back Washburn.
The veteran had an 8-6 record and 2.64 ERA in 20 starts for the Mariners this past season and was traded to the Tigers for left-hander Luke French and Minor League pitcher Mauricio Robles just before the non-waiver Trade Deadline.
But the trade did not work out particularly well for either team.
Washburn had a 1-3 record and 7.33 ERA in eight starts with Detroit and would not have been able to pitch in the postseason even if the Tigers had won the American League Central Division title. French made six starts in August and one in September, going 3-3 with a 6.63 ERA.
Washburn said he began experiencing discomfort in his left (push-off) knee about two months into the regular season, and it got gradually worse.
"The knee limited me to what I could do [for the Tigers]," he said. "I was doing everything possible to figure out a way to get through it, but unfortunately it never happened. But they were very understanding and helpful."
Washburn was shut down for the season on Sept. 15 after surrendering four runs in the first inning in an 11-1 loss to the Royals and underwent arthroscopic surgery in Los Angeles last week -- the first operation in his 12-year career in the Majors.
The knee was "cleaned out" by Dr. Lewis Yocum in Los Angeles and Washburn said Thursday that he should be completely healed before Spring Training camps open in mid-February.
"During the season it would be a four-to-six week thing," he said.
Could Washburn become the most recent of several players -- including Ken Griffey Jr. -- who have had second stints with the Mariners?
The first three years he spent in Seattle were difficult as he struggled to retain the winning touch that allowed him to become an 18-game winner, and World Series champion, in 2002 with the Angels.
He made a lot of starts (91) and pitched a lot of innings (534 1/3), but his 23-43 win-loss record was not what he or the Mariners anticipated.
So going into last season, he was ready to call it a career because the game had stopped being fun for him.
"The year before was not a lot of fun at all," Washburn said of the Mariners' 101-loss season in 2008. "I figured that at the end of my contract, it would be time to go do something else."
But the past 10 months have changed his thinking and he credits the final six months in Seattle he spent as the Mariners' No. 2 starter behind ace right-hander Felix Hernandez and "a great group of guys" in the clubhouse as the reasons for the reversal.
"We had a lot of fun and the coaching staff made it a much more pleasant working environment," he said. "You looked forward to coming to work."
The clubhouse camaraderie made a complete turnaround from the previous season and he admitted to having mixed feelings when the Mariners traded him to the Tigers.
"Going to a first-place team was nice," he said, "but I was leaving a group of players that I loved. It was both good and bad."
Returning to Seattle might be considered a long-shot. The Mariners still have nine pitchers that made at least 10 starts last season, but the drop from Hernandez's team-high 34 starts to left-hander Ryan Rowland-Smith, second with 15, is large.
Unless the Mariners can acquire a veteran starter via trade for a higher-profile free-agent starter like John Lackey, bringing back Washburn at a significantly lower salary could make sense.
While he has no thoughts on the possibility of that happening, Washburn does know that Mariners pitching coaches Rick Adair and John Wetteland helped turn at least one career around.
"It's difficult to explain exactly what happened," Washburn said, "but they worked together with me during the bullpen sessions in Spring Training. They would notice something and were easy to communicate with.
"They saw things that no one else did, simple things in my delivery, made suggestions that had never been made before and it turned me into a better pitcher. Some little things made a big difference."
Jim Street is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.