ANAHEIM, Calif. — All season, the Red Sox have waited for Manny Delcarmen to emerge as their go-to righty in the eighth inning.

It’s nearly August and they’re still waiting.

Delcarmen entered a tie game in the eighth inning yesterday, but soon gave up a two-run double to Casey Kotchman that provided the margin of victory for the Los Angeles Angels of Anaheim.

“He left a changeup up,” Terry Francona said of the pitch in question.

Yesterday was Delcarmen’s first outing of the second-half. He had finished up the first half with 1 1/3 innings of scoreless work against Baltimore on July 13.

But the outing yesterday left him with a 4.65 ERA for the season, and he has allowed runs in almost a third of his appearances (14 out of 44).

The Sox also had Hideki Okajima warming in the seventh, but Francona said Kotchman, a lefty hitter, had had more success against lefty pitchers than righties. Left unsaid by Francona was Okajima’s disastrous history with runners on base this season — he’s allowed 12 of 17 inherited runners to score this year, making the Sox less willing to bring him into games in the middle of innings.

The Masterson option

Delcarmen could soon face some competition for his role from Justin Masterson, who joined the team after arriving here late Saturday night.

Masterson replaced David Aardsma, who went on the DL with a groin strain.

Aardsma originally injured the groin two days before the All-Star break and the Sox thought that the time off would be beneficial. Indeed, when he threw a side session here Thursday during the optional workout, Aardsma was much improved.

But in a brief appearance Friday night in the series opener, he felt a twinge again, and the Sox thought it best to shut him down for two weeks.

“Obviously, it’s holding me back,” said Aardsma, “and the last thing I want is to make it worse.”

Masterson, who was sent to Pawtucket this month to transition to relief, made three appearances for Pawtucket before being summoned.

He said he had “a better feel” for pitching out of the bullpen in the minor leagues, something he hasn’t done since college.

“I’ll pick the brains of some of the guys here (to help make the adjustment),” he said

Masterson could pitch multiple innings, and he could be used as a righty specialist, though Francona said yesterday morning that he wouldn’t want to limit Masterson to that role.

Series to Angels

It may not mean anything until October — if then — but the Sox’ setback yesterday means the Angels will win the season series between the two teams for the first time since 2001.

The teams will meet again at Fenway this month, but the Angels, having swept here and taken two of three at Fenway back in April, lead the series by 5-1. Even if the Sox sweep the Angels this month, the Angels would still hold a 5-4 edge.

That could be important in the postseason if the teams meet. Should they finish with the same record, the edge during the regular season would give the Angels home-field advantage in either the ALDS or ALCS.

The teams have met twice in the last four postseasons, with the Sox sweeping both times in the ALDS. Both times, the Sox went on to win the World Series.

While the Sox continue to struggle at the plate, scoring eight runs and accumulating just 19 hits and a .202 team batting average in the three games, Dustin Pedroia continues to smoke the ball.

He had half their six hits yesterday, doubling in the first, singling in the third and singling again in the seventh.

That extended his road hitting streak to 21 games, third-best for all Red Sox hitters dating to 1956. He has hit safely in all but one of his last 23 games overall, and has multiple-hit games in the last five and nine in his last dozen games.

Against the Angels, he’s hitting .500 (13-for-26) this season.

smcadam@projo.com