KANSAS CITY, Mo. — The Red Sox had just claimed a 9-2 win over the Royals on Wednesday night at Kauffman Stadium, and the music was blaring in the visitors clubhouse.

Van Halen’s “Jump” was the choice this time around, the kind of tune that seemed fit for the polyester-wearing baseball players of the early 1980s, but certainly not this group.

“It’s a nice change, isn’t it?” Red Sox outfielder J.D. Drew said.

The same could be said for the Sox’ not-so-subtle plunging into their postseason preparation. They are positioning themselves for October, with Wednesday night’s lineup serving as one of their first salvos.

It was no great leap of faith to identify the group Red Sox manager Terry Francona sent out there as the Red Sox’ best chance at scoring runs. But when the lineup card was posted and “Martinez, 2” was in the third spot with “Beckett, 1” residing at the bottom of the list, there was no doubt priorities had been identified.

The last gasp Jason Varitek had at seeing a postseason starting lineup — as the batterymate of Josh Beckett — was now being put in doubt, as Martinez had shown enough behind the plate to offer comfort as to be called the team’s full-time, and almost all-the-time, backstop.

The result this time around was a six-run explosion for Boston in the sixth inning, three more in the ninth, and, most importantly, a win.

This made the Red Sox 15-8 with Martinez behind the plate, with the Sox owning a 15-11 mark with Varitek catching since the non-waiver trade deadline. Not a jaw-dropping difference, but enough of one that the subtleties of success with Martinez take precedence.

“There’s that feeling,” outfielder Jason Bay said of his team’s lineup, “that it can happen at any time.”

The foundation for Game 1 of the American League Division Series was potentially being set. Assuming life remains relatively the same for the Red Sox, you will see: Ellsbury CF, Pedroia 2B, Martinez C, Youkilis 1B, Bay LF, Ortiz DH, Lowell 3B, Drew RF, Gonzalez SS.

There might be the argument that if Beckett does indeed pitch that first game, with John Lackey going for the Angels, the offensive advantage of playing Mike Lowell over Varitek is negligible. Lowell has just three hits in 21 at-bats against the LA ace, while Varitek has gone 5-for-27.

But the strength of the lineup Francona trotted out Wednesday night — Lackey or not — has the kind of upside postseason teams drool over.

With Beckett’s affinity for Varitek, it wasn’t an easy decision, but there were reasons for the wheels being put in motion. They are …

THE DEFENSIVE TRADEOFF IS TOLERABLE

One of the perceived problems with going with a lineup that had Lowell at third base and Martinez caching was a drop-off on the defensive side.

But both players have shown enough of late to temper any fears. It starts with Martinez’ ability to not only handle Beckett, but most of the Red Sox hurlers. In 27 innings with Jon Lester, Martinez has guided the lefty to a 2.00 ERA, while the ERA with him catching Clay Buchholz stands at 3.48 over 62 innings.

“He’s not the best catcher in the world,” said one American League general manager, “but he takes it very serious. He’s turned himself into a pretty good one.”

Lowell also isn’t close to the player the Angels saw in Game 1 of last year’s ALDS, when the third baseman found himself playing almost halfway in toward home plate on potential bunters to make up for his lack of mobility.

Now — as his bare-handed play on a slow roller from Baltimore’s Felix Pie over the weekend suggests — Lowell is playing with as much confidence defensively as he has all season.

“I think I had to adjust in June when I felt the swelling in my hip. I felt like I had to play a little more shallow. So for about a two-week stretch I felt I was playing differently, but lately I feel like that quick first-step is back,” Lowell said. “I know running isn’t the greatest thing for me. But defensively it’s only three or four quick steps and you’re either going to make the play or not. I feel really comfortable right now the way things are.”

ORTIZ AND LOWELL ARE HITTING

David Ortiz launched his 25th home run of the season Wednesday night, finishing the game with four RBI and giving him 88 for the season to go along with a .234 batting average.

Since June 1, Ortiz has the sixth-most home runs in baseball (24), and the 11th most RBI (70). As the DH noted, he has come a long way just in the nick of time, as was most recently evidenced by his performance against the Royals.

“I would say a bad season for me is a good season for another guy,” Ortiz said. “Like one of my boys told me the other day, ‘I’ll take your number anytime if I’m going to arbitration.’ ”

He has found his groove, and not forgotten those who said it was a discovery that would never come again.

“I think with the numbers I have already this year, those guys that were checking out my age, I think this should stick in their mind,” Ortiz said. “You know what I’m saying? People thought I was looking for excuses and thinking in the wrong direction when you struggle a little bit. That’s something that, at the end of the day, it’s a sorry analysis. People always have to look at things the right way. Anybody can struggle. Anybody can bump into a bad year. Just see the good things and the positive things.”

Then there is Lowell, who has cooled down somewhat of late, having gone hitless in eight at-bats during the KC series. But he had hit .318 from the time he came off the 15-day disabled list on July 17 through this past weekend.

Just for future reference, Lowell is 5-for-16 off Angels starter Jered Weaver, and 10-for-40 with four homers against LA lefty Scott Kazmir.

VARITEK ISN’T 

The Red Sox captain often limps through the clubhouse, with ice bags on various parts of his body. But no matter what the reason, Varitek has become an offensive liability.

He is hitting .121 this month (4-for-33, 11 strikeouts), after totaling a .135 average in August (7-for-52, 18 strikeouts).

Since the All-Star break Varitek is hitting .156, with the Red Sox claiming a 20-18 mark with him in the lineup.

His average away from Fenway Park is just .183, and he is hitting just .190 from the seventh inning on. With two strikes, he is batting at a .124 clip. All obviously not good.

The other piece of the puzzle that comes into play when Varitek is not in the lineup is the fact that J.D. Drew usually gets inserted into the No. 8 spot, and in the 11 times he has hit eighth, Drew is batting .433.

It all adds up … at least it did Wednesday night, and it figures to once again when the playoffs roll around.