The Red Sox’ J.D. Drew flips his bat in disgust after striking out yesterday.

AP / Ben Margot

OAKLAND, Calif. — Suddenly, it is an all-or-nothing proposition: When the Red Sox play at home, they’re close to unbeatable; when they don’t, they’re virtually hopeless.

In other words, the Sox have become baseball’s version of the NBA postseason.

After yet another road defeat yesterday, 6-3, to the Oakland A’s, the Sox have now negated their 7-0 homestand from last week. The Sox lost the final four games of their last road trip and are off to an 0-3 beginning to this road swing, which has seven games remaining.

“We don’t care,” shrugged Manny Ramirez of the team’s struggles away from home. “We’re right there, right? It’s a long season.”

During series like this, however, it can look eternal. The Sox haven’t had a losing stretch on the road this bad since — gulp —the Joe Kerrigan Era, when they dropped 10 in row in the final month of the disastrous 2001 season.

Catcher Jason Varitek noted that each one of the three losses here were of a different variety. On Friday, the Sox fell behind early to Oakland ace Rich Harden. Saturday, they dropped a taut pitching duel and yesterday they were felled by a variety of issues, including three errors and poor relief work.

“We’ll find a way,” vowed Varitek.

For now, however, they will do from a new vantage point — second place in the American League East, behind the Tampa Bay Rays, whom they trail by a half-game.

Any carryover momentum the Sox might have hoped to gain yesterday from the presence of Jon Lester on the mound dissipated quickly.

Lester, who tossed a no-hitter last Monday against Kansas City, yielded a base hit to the first A’s hitter he faced yesterday, wiping out any chance to become the first pitcher in the last 70 years to toss consecutive no-hitters and setting the tone for a long afternoon.

The A’s scored once in the first off Lester, again in the third and twice more in the fourth.

“All the positives we talked about (after the no-hitter) — getting ahead, dictating the tempo — I did the complete opposite today,” said a rueful Lester. “It seemed like I took a step back today.”

Lester, who threw 130 pitches in his previous start, insisted that fatigue was not an issue yesterday, a fact confirmed by Varitek and Francona.

“His command wasn’t as strong, obviously,” said Francona. “He threw a lot of pitches (94 in five innings), got into some deep counts and left some balls out over the plate. He just wasn’t as efficient today; it had nothing to do with anything else.”

Varitek, as his want, was more positive in his assessment of the outing, strongly disagreeing with Lester’s contention that the pitcher had regressed.

“I wouldn’t call it a step back,” said Varitek. “There’s no way in the world I would call it that. But when he made mistakes, they did some good hitting.”

Emil Brown delievered a two-out run-scoring single in the first and three-base error by Ramirez and single to center from Mark Sweeney produced the second run.

A walk and three straight singles in the fourth pushed the Oakland lead to 4-1 in the fourth before Lester finished strongly, getting the side in order in the fifth, two on strikeouts.

Boston bats, meanwhile, continued to slump. For the series, the Sox managed just six runs. David Ortiz launched a line shot into the right field seats off Jow Blanton in the first.

The Sox had their best chance in the fifth when Blanton fell apart mechanically and filled the bases on walks before Ramirez lashed a single to right, scoring two. But Blanton rescued himself, slipping a called third strike past Mike Lowell with two on and two out.

He then finished off the Sox by fanning Kevin Youkilis, stranding two baserunners.

“One of our characteristics,” said Francona, “is giving ourselves a chance. And we didn’t do much of that today.”

Trailing by just a run in the late innings, the game officially got away from the Sox when Javier Lopez had his first pitch of the afternoon belted into left field seats for a two-run homer by Jack Cust.

Until yesterday, Lopez had stranded 17 of 18 inherited runners. But not yesterday.

It was that kind of day. It has, to date, been that kind of road trip.

The solace for the Sox? As they shift to Seattle, they face a team seemingly incapable of winning anywhere, with the Mariners having lost six in a row.

smcadam@projo.com