BOSTON –– Was Hideki Okajima a one-year flash in the pan?

It’s a question worth asking after another disappointing outing from the Red Sox lefty reliever last night.

Entrusted with a 6-4 lead in the seventh, Okajima faced five hitters and retired only one. By the end of the inning, the Sox’ two-run edge had turned into a one-run deficit. The Baltimore Orioles then tacked on three more runs in the ninth off Craig Hansen for a 10-6 victory.

It marked Okajima’s sixth blown save of the season. Three of those have come against the Orioles, who have certainly figured him out. In four appearances this year, the Orioles have scored eight runs in 5 1/3 innings against Okajima — and that doesn’t include the three inherited runners who crossed the plate when Okajima gave up a grand slam to Jay Payton on May 14.

Inherited runners have been an issue all season for Okajima and are the reason that his 2.89 ERA is highly misleading.

Far more telling is the fact that he’s given up 24 hits in 28 innings of work, a far cry from last season when he gave up just 50 hits in 69 innings of work. Further proof? Last year, Okajima walked 17 hitters all season. This year, well before the halfway point of the season, he’s already walked nine, including two last night.

“He was up with a lot of his pitches,’’ said Terry Francona last night, “and behind in the count.’’

For any pitcher, that’s trouble; for Okajima, that’s disastrous.

Okajima’s fastball, on his best day, hits 88-89 mph. He succeeds thanks to a funky delivery and pinpoint location.

But when Okajima can’t locate with precision, his stuff isn’t good enough to overmatch hitters. With ordinary stuff, Okajima’s margin for error is slight. When he’s off with his command, the results can be ugly.

Last year, Okajima’s success surprised some scouts, who predicted he would become more hittable the more opposing teams saw him. When Okajima faltered in August and September, that seemed prophetic.

But as it turned out, those struggles were more related to fatigue. When the Sox shut him down for a period of 10 days in September, he came back refreshed and as effective as ever. His work in the postseason — particularly five scoreless innings in the ALCS over three games — was invaluable.

This year, however, Okajima has invited renewed skepticism. He’s been nowhere near as reliable in the eighth inning, which has made the Sox far more vulnerable in the late innings.

A year ago, the Sox sometimes struggled in the sixth and seventh innings, but were nearly unbeatable when they held a lead going into the eighth thanks to the duo of Okajima and Jonathan Papelbon.

This year, however, that veneer of late-game invincibility has been stripped and Okajima’s ineffectiveness has been a big reason why.

Left-handed hitters are frequently jumping on the first fastball they see — as Orioles outfielder Nick Markakis demonstrated last night with his double to left.

Equally troubling through all of this is Okajima’s own reaction to his struggles. On almost every occasion that he has faltered, he has refused to answer questions afterward. That speaks to a lack of accountability — not to the media, but to his teammates, almost all of whom behave professionally and are around after games, win or lose.

(In his defense, a teammate last night suggested that Okajima’s postgame disappearing act was a reflection of his embarrassment, and not an unwillingness to take responsibility for his poor showings.)

Further, when Okajima was asked last month about his well-documented problems with inherited runners (14 inherited; 11 scored), he chose not to address them, but rather questioned why Francona continued to bring him into the middle of innings.

Beyond mechanical issues, Okajima’s tough times may be the result of a lack of confidence. Remember, last year, Okajima surrendered a home run on the first pitch he threw in the big leagues, then ripped off a string of 20 consecutive scoreless outings.

That great start provided him with the confidence that he could indeed pitch in the major leagues. This year, Okajima has been seemingly off since the start and has been unable to put together a similar streak.

Perhaps now that he has met with failure for the first time in the big leagues, he must also find a way to overcome it.

For the Red Sox, who are so dependent on him, that discovery can’t come fast enough.