BOSTON — Everything seemed to go the Orioles' way for 5 1/2 innings against the Boston Red Sox on Sunday night at Fenway Park. But after an ESPN nationally broadcast returned from a commercial break for the bottom of the sixth, everything unraveled for the Orioles.

They lost a five-run lead and Gold Glove shortstop J.J. Hardy to injury. Right-hander Ubaldo Jimenez lost his groove with one pitch that was sent into the Boston night, and the sure-handed Orioles defense committed three errors in the final three innings to set the stage for a walk-off loss, 6-5, to the Red Sox.

“That's part of baseball,” Jimenez said. “That's why it's so tough, and sometimes, you feel you have the game in your hand and then everything disappears.”

Left fielder David Lough was charged with a throwing error on the final play of the game when his throw home after catching the second out of the ninth inning was wide of the plate and bounced to the backstop, allowing Dustin Pedroia — who was shuffling between third base and home plate — time to score the winning run to prompt a celebration at home in front of what remained of an announced 33,947.

Orioles manager Buck Showalter, the beneficiary of one umpire-initiated review in the inning, remained on the field to argue for another review to confirm whether Pedroia tagged at third, but he wasn't granted it.

“If he tagged up properly, and if the other two people had tagged up going to the next base,” Showalter said of his appeal for a review. “It's a timing play, though, on the trailers. So, no shot there. Plus you can't appeal a tag. Go figure. They've got some really strange rules. That will change, too, going forward.”

It was undoubtedly the weirdest game of the Orioles' young season.

The Orioles (8-9), who have made it a habit of playing tightly contested extra-inning games at Fenway Park over the past two seasons, might still be playing if any of a number of late plays went their way.

Third baseman Jonathan Schoop, whose seventh-inning throwing error allowed the tying run to score, took blame for not cutting off Lough's throw on the final play.

“I should have caught the throw,” Schoop said. “When the line drive went, I went to the base. As soon as he hit it, everybody was thinking it was a hit, and then I ran to the base because I thought maybe we could catch him [off the bag] and get a double play there. And when he made the catch, I saw Pedroia make the tag. I wasn't able to react to the cutoff.”

The Orioles controlled most of the game Sunday, but they quickly blew a five-run lead after five innings, breathing life into Fenway Park on an emotional night that began with a pregame ceremony that honored the victims, volunteers and first responders of last year's Boston Marathon bombing.

Jimenez held the Red Sox (9-10) scoreless over his first five innings before allowing a three-run homer to Jonny Gomes on a hanging slider to left field on his 107th and final pitch with one out in the sixth inning.

“It was a hanging breaking ball right there, a bad pitch," Jimenez said. "I shouldn’t be making pitches like this, especially in this ballpark.”

After Hardy was forced from the game with a right hamstring strain in the seventh inning, the left side of the Orioles infield committed two costly errors as the Red Sox scored two runs in the seventh to tie the game at 5.

The Orioles might have been out of the inning if not for the highly scrutinized interpretation of the transfer rule, which forces a player to make a clean transfer from his glove to his throwing hand for an out to be recorded.

With Boston third baseman Brock Holt on first base and one out, Grady Sizemore hit a comebacker to left-hander Zach Britton, who threw to Ryan Flaherty for what most likely would have been a 1-6-3 double play.

Even though Flaherty reached out to catch the ball and had possession, he dropped the ball on the transfer, and Holt was called safe at second.

Boston went on to score two unearned runs off Britton. After Pedroia singled to load the bases, David Ortiz singled into right field to score one run. Mike Napoli then hit a ball to Schoop, who just moved from second base to third base, but Schoop wildly one-hopped a throw home, allowing the tying run to score.

“Yeah, you give a good team extra outs, they'll make you pay, and that's what they did to us,” Flaherty said.

Hardy, who missed six games earlier this month with lower back spasms but has never had hamstring problems, won't play in Monday's 11 a.m. series finale.