BOSTON -- As Jon Lester stood in the middle of the Red Sox clubhouse late Tuesday night, tagged with another loss after allowing six runs over four innings, the frustration evident in everything about him seemed as much related to the absence of an explanation as it did to his dreadful results.

“I feel fine mechanically. I feel fine with the process,” the lefty said. “I don’t think there’s anything else I can work on. I work on it every day. Come game time I’ve got to throw the ball better, plain and simple. It’s frustrating showing up every day, busting my (butt), going out there and busting my (butt) when I pitch, and just not pitching well.”

At 28, this is supposed to be Lester’s prime. The expectation was that by now he’d be cemented among the league’s elite — but instead his earned run average says he’s not even average, and that he’s in the midst of a steady regression. In his first full season, Lester had the 13th-best ERA among major-league qualifiers. It was 21st the next year, 25th the year after that, then 32nd last year.

This year it was 86th (of 101) entering Friday, checking in at 4.80 as he heads to the mound to face the Blue Jays this afternoon — but, believe it or not, there is actually some statistical evidence suggesting that Lester actually hasn’t been as bad as his woeful ERA may indicate. And that the supposed staff ace may be poised to turn things around as quickly as his luck will allow.

With the help of fangraphs.com, here are eight reasons for the Red Sox to keep hope:

-- Batting average on balls in play — On balls put into the field of play, opponents are hitting .331 against Lester. That’s the ninth-highest mark in the game, which says balls off the southpaw have happened to find holes more frequently than they have against all but eight pitchers in all of baseball.

-- Fielding independent pitching (FIP) — This aims to determine what a pitcher’s ERA would be if the variables of batting average on balls in play and timing were removed from the equation, and Lester comes in at a respectable 3.67. That’s right in line with his career number of 3.65, and 33rd in the majors – again suggesting he’s been victimized by bad luck, and things are could even out.

-- Strand rate — Of the runners that reach against him, Lester is allowing more of them to score than ever. He’s stranding only 65.7 percent, which is sixth-lowest in the game. For his career he’s at 75.2 percent, which suggests his general misfortune has bit him at inopportune moments.

-- Velocity — The high-end heater isn’t there. Lester has hit 95 mph in just four of 19 starts this year; in only four outings did he fail to hit 95 in all of 2009. But generally his velocity has been just as consistent. His average fastball has been 92.2, compared to 92.7 for his career, which indicates there hasn’t been a huge falloff in arm strength.

-- Fenway struggles — Lester’s ERA on the road is 3.04. His rate of walks and hits per inning pitched away from Fenway is 1.11. His stuff is still good enough; it’s the inconsistency that’s plagued him.

-- Swinging at balls — Speaking of “stuff,” Lester has prompted batters to swing at 31.3 percent of the pitches he’s thrown outside the strike zone — a career-high implying the action and movement on his pitches is enticing enough that hitters will stray.

-- Pitch mix — Lester is mixing his arsenal better than he has in the past. Last year he blamed his occasional struggles on being too reliant on his cutter, which he used for 27.9 percent of his pitches. This year, his cutter, changeup and curveball have all accounted for between 12.8 percent and 16.7 percent of his throws. Once he improves his execution on them, he’ll have his enemies off balance.

-- Walks — After climbing to disconcerting levels in 2010 and ’11 (3.6 and 3.5), Lester has lowered his walks per nine innings to 2.6. If he maintains that, it would be the best rate of his career — so, again, he’s not far off. He’s just not making pitches. And though he doesn’t yet have an answer how to make that happen, that doesn’t mean it won’t.

“I’ve got to do a better job executing pitches, and I’m just not doing it right now,” he said. “It’ll turn.”

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After Cody Ross crushed his third three-run homer in two nights — this one giving the Sox a walk-off win on Thursday — Bobby Valentine recalled receiving a call from general manager Ben Cherington when his right fielder was brought into the fold over the winter.

“I remember the excitement in Ben’s voice when he said, ‘We’ve got a player who’s really going to help us,’” said the manager. “As an announcer, I did some of Cody’s postseason and some of his San Francisco stuff. I love his smile, I love his swing, I love his energy.”

For $3 million, Ross began Saturday with the AL’s 10th-best on-base plus slugging (among those who’d played more than 30 games) — but he’s only committed to the Sox through this season. And that could make the next nine days interesting as the Sox approach the trade deadline.

If the team is interested in bringing Ross back next year, and Cherington believes he’d have a good chance of signing the player, he may be more willing to part with someone like Ryan Kalish to sweeten a potential deal designed to improve the team immediately. If it still sees Kalish as next year’s starting right fielder, though, it may not be willing to move more than Ryan Sweeney or Daniel Nava from its outfield.

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STAT OF THE WEEK: The Red Sox entered Saturday night’s tilt having split their last 12 games. In games started by Lester or Josh Beckett, Boston was 1-4 in that span; with anyone else pitching, the Sox were 5-2.

Dave D’Onofrio covers the Red Sox for the New Hampshire Union Leader and Sunday News. His e-mail address is ddonof13@gmail.com.