Under Valentine's watch, the Red Sox finished with a 69-93 record, the worst the tradition-laden franchise had experienced since 1965.
VALENTINE'S MANAGERIAL RECORD
"Our 2012 season was disappointing for many reasons," said general manager Ben Cherington, who made the announcement and who will lead the search for a successor. "No single issue is the reason, and no single individual is to blame. We've been making personnel changes since August, and we will continue to do so as we build a contending club. With an historic number of injuries, Bobby was dealt a difficult hand. He did the best he could under seriously adverse circumstances, and I am thankful to him."
Boston finished in last place in the American League East for the first time since 1992.
Valentine had one year left on his contract.
The first time Valentine's job security -- or possible lack thereof -- became a topic was early August, after the Red Sox had lost three out of four to the Twins.
But on Aug. 6, prior to a home game against the Rangers, Cherington and principal owner John Henry both issued votes of confidence for the manager, at least saying he was their guy for the rest of the season.
Was there any consideration to making a change at that time, with the Red Sox just four games back in the Wild Card standings?
"Not very much," said Red Sox president/CEO Larry Lucchino. "Our view was that ... it's been pretty consistent, we were going to wait until the end of the season to make any kind of changes or to do any kind of thorough diagnosis. We talked from time to time, but the plan had always been to complete the season."
Perhaps there were simply too many issues with the team to think a managerial change could have saved the season.
"We were trying to diagnose what was going on with the team and looking at a lot of different things," Cherington said. "As Larry said, we never really considered changing the manager at that point. We were looking at a lot of different things that weren't going as well as they needed to. There was never any focus on changing the manager at that point."
Things never improved. In fact, they only got worse. The Red Sox never contended for a postseason berth in 2012, as Valentine faced several challenges that he and the team could not conquer.
"I understand this decision," said Valentine in a press release issued by the Red Sox. "This year in Boston has been an incredible experience for me, but I am as disappointed in the results as are ownership and the great fans of Red Sox Nation.
"It was a privilege to be part of the 100-year anniversary of Fenway Park and an honor to be in uniform with such great players and coaches. My best to the organization. I'm sure next year will be a turnaround year."
After the worst September collapse in Major League history last season, the Red Sox parted ways with Terry Francona, considered by most to be the best manager in team history. Following a two-month search for Francona's successor, the club chose Valentine, who hadn't managed in the Major Leagues since 2002, when his tenure with the Mets ended. Filled with emotion, Valentine was unveiled at a packed Fenway Park news conference on Dec. 1.
Known at past stops for being at the center of controversy, Valentine was involved in plenty of it in Boston, mostly because of his candid nature.
Things started to get stressful for Valentine after the ninth game of the season. Valentine noted during a television interview that third baseman Kevin Youkilis didn't seem to be playing with the same passion as in years past.
The criticism stung Youkilis, and Dustin Pedroia went to bat for his then-teammate, saying of Valentine, "That's not the way we do things here."
The story lingered for weeks, and Youkilis was traded to the White Sox in June.
Before his final game as Boston's manager on Wednesday, the 62-year-old Valentine mentioned the comment about Youkilis as something he regretted.
"I didn't expect that reaction," he said.
It's fair to say that the way Valentine conveyed things -- either through the media or directly to his players or superiors -- might have contributed to the team parting ways with him after just one year. But the Red Sox wouldn't confirm that assertion.
"We're not going to get into specific topics or issues or diagnosis of problems," Lucchino said. "On balance, the record speaks for itself. There are numerous factors that contributed to it, and by no means does the blame for this season fall on or exclusively on Bobby Valentine, or exclusively on him. We all share some full measure of accountability for the dismal year we presented."
Now the search begins in earnest for a new manager.
"First of all, we're not prepared to talk about names," said Cherington. "It's too early to do that. We know that there needs to be a bit of a reset with the culture in the clubhouse. We've lost too many games for the last seven months of play, Major League play, so that has a sort of wearing down, can have a certain wearing down effect. We need to revitalize a clubhouse, the manager's part of it -- the manager's not the only part of it -- but the manager's part of it. We need someone to help us accomplish that."
Perhaps some of the controversy that surrounded Valentine would have gone away if the club had played better. But the 2012 Red Sox -- ravaged by injuries and underperformance -- never got on any kind of roll.
"This year's won-loss record reflects a season of agony," said Lucchino. "It begs for changes, some of which have already transpired. More will come. We are determined to fix that which is broken and return the Red Sox to the level of success we have experienced over the past decade.
"Difficult as it is to judge a manager amid a season that had an epidemic of injuries, we feel we need to make changes. Bobby leaves the Red Sox's manager's office with our respect, gratitude and affection. I have no doubt that he will continue to contribute to the game he loves so much and knows so well."
Cherington, Lucchino and Henry all praised Valentine for the professionalism he showed in taking the news.
"I've been a part of several managerial changes over the course of my career, and I think Bobby Valentine ended it with more dignity and class and constructiveness than anybody I can remember," said Lucchino.
Regardless of who the next manager is, the Red Sox vowed to restore the franchise to where it was in the first decade of current ownership, which started in 2002.
"I will mention that in the first 10 years we were here under this John Henry and Tom Werner ownership, we have averaged over 92 wins a year for 10 years and none of us is smart enough of skillful enough to keep that going indefinitely," Lucchino said. "This is an ebb and flow, cyclical kind of business. We just experienced that in full measure."
Red Sox chairman Tom Werner said, "This season was by far the worst we have experienced in over 10 years here. Ultimately, we are all collectively responsible for the team's performance. We are going to be working tirelessly to reconstruct the ballclub for 2013. We'll be back."
Henry said, "In our meeting with Bobby today, he handled everything with dignity and class, and it is deeply appreciated. Ultimately, we as owners are responsible for arming our organization with the resources -- intellectual, physical, and financial -- to return to the levels of competitiveness to which we aspire and to which our fans are accustomed. Our commitment to winning is unwavering. It is a commitment to this team, to this city, and to these fans who have supported us through thick and thin.
"We have confidence in Ben Cherington and the kind of baseball organization he is determined to build."
It is Cherington who will again pioneer the search for the manager. Lucchino continues to take offense to the notion that ownership strong-armed the GM into hiring Valentine last winter.
"I think the question is based on a false assumption, it really is," Lucchino said. "Ben led the search last year. He's going to lead the search this year. The decision, there will be recommendations made along the way, but the decision will ultimately be a consensus decision made by Ben and myself and John and Tom. But Ben will begin the leadership search immediately."
In his two previous stops as a Major League manager, with the Rangers and Mets, Valentine provided a spark during the early years of his tenures.
The Red Sox were hoping for a similar impact, but it never occurred.
The final six weeks of the regular season became highly challenging for Valentine when the team made a blockbuster trade that was geared toward the future, sending Adrian Gonzalez, Josh Beckett, Nick Punto and Carl Crawford to the Dodgers for James Loney and prospects.
Playing with a lineup stocked with players who opened the season in Triple-A, the Red Sox finished the season in a free-fall, losing eight in a row, 12 out of 13 and 26 out of 33.
"Yeah, it was trying," Valentine said. "I don't know how it could be more challenging than this season."
On Wednesday, Valentine said he had no regrets about taking the job.
"It's a great life experience," Valentine said. "That's what life is. It wasn't always an enjoyable experience, but it's been great. One I'll look back on and I'm sure I've learned from."