BOSTON — Execution in all aspects of the game has been something of a given of late for the Red Sox.

At the plate, in the field and on the base paths, the Sox have done all the proverbial little things to increase their lead in the A.L. East. With veteran pitcher Curt Schilling on the mound last night, Boston was hoping to increase its winning streak to five games, but the bullpen imploded and the fundamental act of bunting proved too difficult.

Schilling left the game with a one-run lead after six innings, but reliever Manny Delcarmen allowed the game-tying solo home run to Troy Glaus in the eighth inning and Hideki Okajima surrendered a two-run homer to Vernon Wells in the ninth as the Jays defeated Boston, 6-4, last night at Fenway Park.

“Manny got behind a dangerous hitter, came in with a fastball and didn’t come in far enough and (Glaus) hit it a long way,” said Red Sox manager Terry Francona. “[Okajima] left an off-speed changeup up over the plate (to Wells). That’s going to happen. … Guys aren’t going to be perfect out of the bullpen. That’s the way the game is.”

Delcarmen had been solid of late, but he just didn’t make the pitch when he needed to.

“I completely missed my spot,” he said. “I was trying to go down and away and it ran back in. … Now’s the time everybody has to pick each other up, and I didn’t do it tonight.”

There’s been some concern that Okajima, who has been solid for the majority of the season, is beginning to tire because of the workload he’s taken on this season, his first in the majors. The crafty lefty was asked after the game if, in fact, he is tired.

“As you see, yes,” he said before hesitating and changing his answer. “I don’t know.”

Entering last night’s game, Okajima had allowed six runs in his last 13 games (12 2/3 innings) to raise his ERA from 0.87 to 1.54. In fact, he has allowed a run in just 10 of 61 games this season, but the two he surrendered last night were big.

“If he keeps that ball down, it’s a different story,” said Red Sox catcher Jason Varitek. “You make mistakes. He made a mistake.”

Offensively, in fundamental situations, the Red Sox shot themselves in the foot, both times attempting to execute a sacrifice bunt with two veterans — Alex Cora and Coco Crisp — the guilty parties.

“I didn’t do the job,” said Cora. “I’ve got to turn the page, but I don’t think only one play cost us here.”

With the Red Sox trailing by two runs in the fifth inning, Cora stepped to the plate with two on and no outs. He couldn’t get the bunt down and eventually struck out. Crisp had a similar situation in the eighth inning with the game tied at 4-4.

Varitek led off the bottom of the inning with a single, but Crisp popped up a bunt attempt to the catcher for the first out of the inning. Cora reached on a fielder’s choice as Varitek was out at second. Julio Lugo grounded out to short for the final out of the inning.

“We had opportunities tonight and we didn’t execute,” said Francona. “We had a couple of situations that hurt our chances.”

Schilling is now 2-1 with a 3.96 ERA in his last four starts. He was solid for the first three innings last night, retiring nine of the first 11 batters he faced, and with the help of some solid defense worked out of a threat in the fourth inning. He entered the top of the fifth inning with a 1-0 lead thanks to J.D. Drew’s RBI single back in the first, but then the Blue Jays hitters got to him.

Toronto scored three runs on four hits for a 3-1 advantage, but Boston pushed across another run in the bottom half of the inning on Ellsbury’s sacrifice fly. Schilling made quick work of the Blue Jays in the sixth, and the Sox regained the lead in the bottom of the inning when Varitek launched his two-run shot.

Schilling was done after six full innings and surrendered just three runs on eight hits with a walk and two strikeouts.

“When he made his pitches he was fine,” said Francona. “When he made mistakes he got hit. When he makes his pitches he goes right through the batting order.”

Reliever Bryan Corey, who was called up from Pawtucket on Saturday, worked a scoreless seventh. In the top of the eighth he was replaced by Delcarmen, who surrendered a one-out, solo home run to Glaus as Toronto tied the game at 4-4.

Wells smoked a two-run homer into the center-field bleachers off Okajima in the top of the ninth and Toronto held on for the win.

The Sox now head to Baltimore for a four-game set against the Orioles that starts tonight.

jmcdonal@projo.com