TOKYO — Every member of the Red Sox came a long way to begin the 2008 season here, but in a very real sense, no one has journeyed as far as Jon Lester.

A year ago, Lester was chafing in his bid to convince the Red Sox that, rid of the non-Hodgkin’s lymphoma that had threatened his life months earlier, he was ready to pitch again.

Wisely, the Red Sox made sure he progressed slowly, fearing that having him do too much too soon, with an already weakened immune system, would have disastrous consequences.

As Lester prepares to make his first start of 2008, no such fears exist. To the contrary, the Red Sox are trying to tamp their own expectations for Lester, whom, they believe, is ready to emerge as a formidable starting pitcher.

It’s a belief that was first realized last October, when Lester started and won Game Four of the World Series, shutting out the Colorado Rockies for 5 2/3 innings in the title-clinching game.

“My feeling today,” pitching coach John Farrell said, “is no different than at the end of last year — this is a guy who’s ready to become a solid, middle-of-the-rotation starter. The progression he’s made in the last year is pretty remarkable.”

Farrell and the rest of the Red Sox’ staff have been taken by what Farrell terms the left-hander’s “relentless work ethic and his competitive instincts.”

The Sox saw evidence of that with Lester as far back as 2006, before he was diagnosed with his illness. They saw a determined rookie who, rather than succumb to the temptation of throwing a fat pitch after falling behind a hitter, would begrudgingly issue a walk instead.

That mental toughness, the refusal to give in, already was part of Lester’s DNA. What wasn’t always present was his command, forcing him into high pitch counts and often, early exits.

In hindsight, Farrell now wonders whether the onset of Lester’s illness led to his struggles. Was Lester too weakened by the cancer growing in his body to regularly repeat his delivery? Were his struggles internal rather than the result of faulty mechanics?

“That’s the great mystery that we may never know when the story of Jon Lester is told,” Farrell said.

What Farrell and the Sox know is that Lester experienced a pitching epiphany of sorts late last season. During a routine side session in Tampa Bay, Farrell suggested a simplification of his windup. Rather than raising his arms fully over his head when pitching out of the windup, Farrell suggested a more compact delivery.

It proved the perfect elixir, and in fact unwittingly had Lester revert to the approach he used in high school.

“So even though I thought it was something new,” Farrell said, “he went back to something that was customary. He had less movement [with his body]. He didn’t block off his front hip, he was standing up a little straighter and it helped his ability to throw to both sides of the plate.”

Soon, Lester’s command improved dramatically. He got ahead of hitters quicker, put them away faster and was generally more efficient. In the ALCS, he struck out five and walked just one in two relief appearances, then capped his comeback season with his sterling effort in Game Four.

This spring, Lester appears considerably stronger, having added nearly 20 pounds of muscle thanks to an off-season conditioning program. Blessed with more stamina and more in control of himself on the mound, Lester’s career begins again tomorrow here in the second game of the season.

“He wants [the illness] totally behind him,” Farrell said. “He’s in an endless pursuit to be the best he can be and what he’s realizing now, I think, is his true potential.”

There are no restrictions, no debilitating chemotherapy sessions, no emotional downturns. For the first time in a long time, Lester can be all about merely pitching and he’s attacking this season as if he’s making up for lost time.

And the Red Sox are fascinated to see how good he can be.

“Everything now is geared toward attacking hitters and executing the game plan,” Farrell said.

smcadam@projo.com