BOSTON, AUG. 22 -- Ben McDonald picked a costly moment for his first big-league shelling and Mike Boddicker crafted a painful reminder to the Baltimore Orioles that their past is quite a bit more glorious than their present.

Together those elements put the Boston Red Sox on their way to a 13-2 pasting of the Orioles this afternoon before 35,189 at Fenway Park. The Orioles hadn't given up that many runs in a game all season and hadn't lost by a larger margin. The rout left them at least temporarily on the outside of a two-team race in the American League East as the stretch run begins in earnest.

They lost what Manager Frank Robinson a day earlier had called a must-win game. This was their second defeat in three games here, dropping them eight games behind the first-place Red Sox.

They will play 22 of their next 29 games at home and have 10 games left with Boston and the second-place Toronto Blue Jays. But the Orioles have lost six of their last eight, nine of 13, and 11 of 16. They're 2-8 against the Red Sox and trudge home both battered and fully aware of their predicament.

"We're really up against the wall now, huh?" reliever Gregg Olson said. Robinson was not willing to concede that today's loss multiplies the sense of urgency that will accompany the rest of the season, but said: "We have to do it. We have to put something together."

The Red Sox improved to 66-56, including 39-21 here. They've won 10 of their last 12, and 22 of 26 at home. Asked if today officially had reduced the East to a sprint between his club and the Blue Jays -- two games behind after losing, 4-2, tonight in New York -- Red Sox Manager Joe Morgan replied: "Unofficially."

McDonald threw 85 pitches, the same number he needed to shut out the Chicago White Sox on four hits in his first major league start a month ago. But the Red Sox punished quite a few of his deliveries, sending him to the earliest shower of his brief career with a 3 2/3-inning, five-run pounding that raised his ERA from 1.86 to 2.53.

He struggled with his control and lacked the usual zip on his fastball and knee-jerking bend to his curve. He had been in that predicament before, however, and gotten by. But the Red Sox were unforgiving, taking full advantage of their four hits and four walks (his career-high) and sending McDonald to his second defeat after he'd won his first five starts.

"I never did feel totally comfortable out there, even in the first three innings," he said. (That was when he allowed two walks but no hits.) "I just wasn't throwing the ball where I wanted to throw it . . . I thought I had a decent curve today, but I was always behind in the count and never could throw it very much."

The Red Sox sent nine men to the plate during a five-run fourth inning that finished McDonald and included Ellis Burks's two-run home run and Jody Reed's two-run double. McDonald might have escaped with a 2-0 deficit after Burks's homer, but left fielder Joe Orsulak lost Mike Greenwell's fly ball in the sun for a double and Boston got the last runs of the inning on Reed's two-out hit.

"You look back on the out he should've had, and it should've been 2-0," Robinson said. "I wouldn't call that the wheels coming off. {McDonald} wasn't real sharp. He just lost some concentration and kind of let the game get away.

"He's not going to come in and just turn this league on its ear. He's going to have good days and bad days, hopefully more good than bad. It's still a learning experience for him."

Greenwell added a two-run homer off Jose Bautista an inning later, and the 7-0 cushion never was threatened. The Red Sox put the final, cosmetic touches on in the eighth with a six-run uprising off Jeff Ballard. Luis Rivera hit a towering, three-run home run into the net above the Green Monster in left field for a 10-2 lead, and Boston got three runs more with two outs.

The Red Sox finished with 11 hits and their fifth three-homer game of the season. Burks went three for five and Greenwell added two hits. Tony Pena, who had two three-walk games in his 10-year career before this series, had his second straight today. And the Red Sox, homerless in eight consecutive games until Tuesday, totaled four homers in two days.

Boddicker (12-8) began sluggishly but toughened as the game progressed in improving to 3-0 this season and 4-1 lifetime against his former team. He had been winless in his previous eight starts, but the Orioles let him off the hook by stranding five runners in the first four innings -- three of them at third base -- and hitting into three double plays.

Morgan was booed lustily for removing him with two outs and two on in the eighth and his shutout intact. But Boddicker had a flare-up of the back spasms that have plagued him the last two weeks, and he had told Morgan as early as the sixth to have someone ready to replace him.

Beleaguered Rob Murphy followed and yielded runs on back-to-back pinch-hit singles off the left field wall -- the first by Ron Kittle for his first RBI since July 18, 12 days before he was traded to the Orioles for Phil Bradley. So Boddicker's pitching line became a little less nifty, but that hardly detracted from his performance.

He had two runners aboard with one out in the first and induced Sam Horn to hit into a double play. He struck out overmatched Chris Hoiles on three of his trademark "dead fish" breaking balls on his way to wriggling free from a first-and-third, one-out jam in the second.

A double play got him out of comparatively trouble-free third, and strikeouts of Bob Melvin and Hoiles left runners at second and third in the fourth.

"Bod is Bod, but let's not say it's just Bod," said Robinson, whose team entered the day leading the major leagues in men stranded and left nine more this afternoon. "We've been doing it to ourselves all season. That's probably been our biggest problem all year long."

Boddicker, who had not given up an earned run in his last two starts here but had two defeats to show for his efforts, was the Orioles' last link to their mantlepiece staffs of the early 1980s until they traded him to the Red Sox two years ago.

He seemed to take little satisfaction from delivering what may be the death blow to his old club. After all, he said, Brady Anderson -- one of two players Baltimore received in the deal -- had gone two for four off him.

"There's no animosity," Boddicker said. "I have fond memories of my time there. They treated me well. I can't say I'm sorry though. All's fair in a pennant race."

Orioles Notes: Anthony Telford will make his second big league start Friday, against the Cleveland Indians, as the Orioles begin a seven-game homestand. . . . Today's crowd brought the total for the series to 105,271, making this the best-attended three-game set in Fenway history.