If this most improbable mission is going to be completed, it is most fitting that it happen tonight with John Lackey on the mound at Fenway Park.

No one has been more reviled (sometimes fairly but often unfairly, including by yours truly) since coming to Boston. No one became more a symbol of the frustrations and failures of the 2011-2012 Red Sox than he.

But tonight John Lackey, like his team, can change the narrative.

Together they can erase the memory of it all just as they have removed the stench that once surrounded them with incredible effort and attitude this magical season. All John Lackey has to do is win one of the biggest games of his career, and he will receive a plenary indulgence from the gods of baseball and the patrons of Fenway Park.

All sins will be forgiven. His baseball soul in Boston will become as pure and white as a lamb’s fleece because if it goes right tonight he will forever be The Man.

All he must do is win the final game of a World Series for the second time in his career, something only six starting pitchers have ever done. All he has to do is join a club so exclusive it includes only Sandy Koufax, Bob Gibson, Art Nehf (who?), as well as Lefty Gomez, Vic Raschi and Andy Pettitte, who all did it for the Yankees so we don’t care.

Koufax, Gibson and Lackey? Not what you might have expected a year or two ago, but if he can put his name in that sentence he will change forever how Boston perceives him.

“We had a great group of guys, great chemistry, you could feel, from the start and had a lot of guys with some rings, a lot of guys that have been on playoff teams,” Lackey said yesterday when asked how this came to be. “Our expectations were high. We definitely wanted to make the playoffs and once you get in the playoffs, you never know what can happen at that point.

“Obviously I’m not even ready to think about that yet,” he said when asked what this year has meant after all his trials in Boston. “I’m focused on trying to make some pitches, trying to help this team win. There will be time for that later on.”

Signed to an $84 million free agent contract no one but Theo Epstein could fathom, Lackey came to Boston with a reputation of being a good guy and a consistent pitcher who ate up innings. And for two years he seemed to be neither.

His personal life and his right arm were hanging in tatters, and so he suffered like anyone might when they have troubles on the job and deeper ones at home. Eventually he would go through a difficult divorce, and then require Tommy John surgery to put together an elbow which had enough of throwing baseballs summer after summer.

Lackey pitched through considerable pain in silence in 2011 and got little credit for it. He never came off as sympathetic because, well, he wasn’t willing to ask for your sympathy. He may have complained a bit more than the average fan likes about the vagaries of baseball and the difficulties of pitching at Fenway, but never about the fact his arm was killing him.

He was a bulldog, but you only get credit for that if you win, which neither he nor the Sox did when it counted most in 2011, losing 20 of their final 27 games in a hail of bad baseball and worse diets. Chicken grease with a beer chaser stained their collapse, cost Terry Francona his job and began a rapid demise that now has left Lackey and the Sox in the oddest of circumstances.