BOSTON — Another home game, another win. So what else is new?

That would be 17 of 19, 19 of 22 and 26 of 31 at Fenway for the Red Sox, who can’t seem to lose at home.

The just-completed homestand, capped by last night’s 9-2 win over Baltimore, left the Sox 7-2 for this stretch. Of the 11 home series the Sox have played, they’ve won all except one.

The road? That’s another story, one that begins again tonight with the first of six away from Fenway. The Sox will play three in Cincinnati and three more in Philadelphia before returning for a homestand a week from today.

The trip will pit two tendencies against one another. The Red Sox have been unstoppable against National League teams the last few years (31-8 since the start of 2006), but unsuccessful on the road this season (14-20).

Forget nature or nurture. In the next week, we’re about to find out which is more important –– opponent or location?

“Something,” agreed Mike Lowell, whose grand slam propelled the Sox last night, “has to give.”

There are, as Lowell and others pointed out, no easy explanations for the Sox’ home-road disparity.

“I wish I could say it’s this or that,” Lowell said, “because then we could take whatever it is on the road.”

Much of the team’s road slump has been circumstantial. The first seven road games, remember, came in Japan, Oakland and Toronto, covering some 10,000 miles –– hardly the typical trek.

Last trip, the Sox began on the West Coast, then, following a day off, finished in Baltimore.

This one –– two three-game series — is more “what a road trip should be,” Lowell said. “You can kind of get into a little bit of a routine.”

But particulars aside, the Red Sox simply — and obviously — need to play better on the road.

“If we play the way we’ve been playing,” vowed Lowell, “we’re going to win a lot of ball games –– wherever we are.”

In other seasons, the Sox might be hurt by visiting a National League city since it would force the Sox to choose two from the trio of Lowell, David Ortiz and Kevin Youkilis. With no DH available, the Sox would be, by definition, diminished offensively.

But with Ortiz on the disabled list with a wrist injury, he’s out of the equation. Instead, the Sox will have to make a decision between Coco Crisp and Jacoby Ellsbury.

To date, the Sox haven’t missed Ortiz as much as might be expected, thanks to J.D. Drew’s torrid stretch. In the last 11 games, which exactly coincide with Ortiz’s absence, Drew is hitting .500 with 6 homers, 5 doubles and 15 RBI.

And there’s this to consider: Drew last year crushed National League pitching (.328, 4 homers 13 RBI), even as he struggled mightily at other times. If Drew can continue to smoke the ball over the next two series, the Sox stand an excellent chance of returning with a winning record next week.

Whatever the reason, whatever the solution, now would be a good time for the Sox to find the answer.

“We’re going to try and figure that out on the flight,” said Terry Francona, “because we haven’t figured it out very well to this point. I know our guys love playing (at Fenway) –– they’d be crazy not to. The atmosphere may be the best in baseball.

“But there needs to be more of an explanation than that and hopefully we’ll figure it out. Because ultimately, if we want to get to where we want to go, we’re going to have play better on the road.”

Across baseball this season, it’s been tougher than ever for teams to win on the road and the Red Sox are no exception. In the American League, heading into yesterday’s action, visiting teams won just 43 percent of the time. With their 14-20 record away from home, the Sox are winning at a 41 percent clip, below the league average.

Now would be a good time for the Sox to start figuring out their road woes. Starting tonight, the team will play 16 of their next 22 on the road.

Between now and then, there will be good teams (Philadelphia, Tampa), average teams (New York, Houston) and bad teams (Cincinnati).

By the time that stretch is complete, the Sox will be nearly at the All-Star break. By then, it should be clearer whether the team’s performance on the road was a two-month aberration –– or something that could prove to be serious obstacle to their repeating as World Series champions.

smcadam@projo.com