In spring training, the goals were modest. If Jon Lester could manage, say, 170 or 180 innings, the Red Sox would have every reason to consider his first full season in the rotation a success.

Now, with three weeks left in the season, Lester has already cleared that bar, and may exceed such standards as a pole vaulter in a high jump contest. Despite crashing through his career innings high, he remains armed with a pitching arsenal that is as good as it has been at any time this season.

In last night’s 3-0 blanking of the Tampa Bay Rays, Lester (14-5) fired 7.2 shutout innings while fanning nine. He has now thrown 189.1 innings this year, the most by a Boston left-hander since Frank Viola logged 238 frames in 1992.

Yet Lester’s stuff has remained fresh, particularly of late. He has allowed one or fewer runs in three of his past four starts, and suggested that newfound consistency and efficiency of his mechanics has allowed him to grow stronger as the season has progressed.

Last night, his fastball showed mid-90s power, his cutter splintered bats and his dirt-kissing curve left Tampa’s hitters flailing. At a time of year when pitchers are usually running on fumes, Lester appears to be downshifting.

“His velocity,” noted Tampa Bay manager Joe Maddon, “is way up from where it had been in the past.”

“The ball’s coming out of his hand better now than it has any time all year,” agreed Sox manager Terry Francona. “He looks like he’s built to give you a lot of innings. His delivery is solid. He’s a big strong kid. He seems to be getting stronger.”

Francona is certainly managing as if that is the case. Last night, though Lester had thrown 105 pitches through seven innings, he went back out for an eighth inning of work.

In one sense, the development was surprising. In the past, Lester acknowledged, he might have been asked to call it a night at such a juncture. Yet this year, he has demonstrated to the Sox that he is capable of maintaining his performance deep into games.

Prior to last night, opponents had just a .222 average, .282 OBP and .250 slugging percentage against Lester after the pitcher had reached 100 pitches. (Those marks were all lower than for any 25-pitch increment up to 100 pitches.)

The move did not pay off in full against the Rays last night. Lester allowed a two-out single to Ben Zobrist and a two-out ground-rule double to Carlos Pena, prompting the move to Jonathan Papelbon, who struck out Rocco Baldelli to end the lone Rays threat. All the same, the starter was delighted to have his manager’s trust at that stage of the game.

“It’s hard to tell this year when you’re done. (Francona), it seems like, has been trusting me to go a little bit deeper in pitch counts,” said Lester, who exceeded 115 pitches for a team-leading fourth time this year. “It’s been fun for me to have that trust from my manager and the team.

“Just because I’m at 105 pitches doesn’t mean I’m done with the game,” he continued. “I’m physically more mature, mentally more mature, so I can handle 110, 115 pitches. Whereas last year and the year before, it was right around 100.

“They didn’t want to take a risk with high innings totals or high pitch counts. This year, it seems that they’re putting a little more trust in my work ethic and me, as a pitcher, to go out there and throw more pitches.”

That trust, of course, has been earned. Lester is producing the most compelling season by a Red Sox southpaw in a generation.

With two more wins, he would have the most victories by a Sox lefty since Bruce Hurst’s 18 in 1988. Lester’s 3.23 ERA—fifth in the American League—is the lowest by a Boston portsider since Viola’s 3.14 mark in 1993.

Excellence and innings have both been routine. Lester has gone six or more innings in 20 of his 30 starts this year, producing a team-high 18 quality starts. In an average outing, he has asked the bullpen to pick up fewer than three innings of slack.

The contrast with his first two part seasons in the majors is striking. In his first 26 big-league starts in 2006 and 2007, Lester managed to pitch six innings just 12 times, with 10 quality starts. Now fully healthy, he has been a workhorse who has proven capable of dominating any caliber of opponent.

“Jonny Lester has really turned the page into being an elite-type guy,” said Sox third baseman Mike Lowell. “I think early on last year, in ’06, the consistency wasn’t there. But that’s part of experience. You learn yourself and you learn the adjustments. When he’s throwing strikes, he’s got such good stuff. He’s got a lot of pitches that hitters don’t like to face."

Remarkably, that seems to be even more the case in September than it was earlier this year.

Alex Speier is a Senior Writer for WEEI.com.