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BOSTON – Infielder Terrin Vavra is in Boston today on the medical taxi squad. He hasn’t appeared with the Orioles this season.

Vavra is hitting .317 with a .838 OPS in 22 games with Triple-A Norfolk.

The club didn’t specify why Vavra is here, but outfielder Ramón Laureano remains out of the lineup and did some running earlier to test his left ankle.

The tarp is on the field again and rain fell earlier, but the Orioles should be able to play their split doubleheader at Fenway Park.

Zach Eflin gets the start in Game 1, with the Game 2 starter unannounced. Left-hander Trevor Rogers is a possibility as the 27th man. Charlie Morton was expected to pitch today before last night’s rainout.

Eflin has made five starts and posted a 5.08 ERA in 28 1/3 innings. It blew up after he allowed eight runs, along with 10 hits, in 5 1/3 innings against the Nationals.

The veteran right-hander faced the Red Sox on April 2 in Baltimore and allowed three runs in six innings. He has a career 5.00 ERA against them in seven starts and is 2-0 with a 6.43 ERA in two starts in Boston.

Rafael Devers, who had eight RBIs last night, is 7-for-19 with four doubles and two home runs against Eflin. Trevor Story is 6-for-13 with two doubles and a homer. Wilyer Abreu is 5-for-13 with a double and home run.

Emmanuel Rivera is playing first base in Game 1. Ryan Mountcastle is the designated hitter and Ryan O’Hearn is in left field again.

Ramón Urías is the third baseman and cleanup hitter. Heston Kjerstad is in right.

The Orioles have lost nine of 10 games and 15 of 18. They’re 16-33, including 8-18 on the road, and 13 ½ games out of first place.

Their minus-99 run differential is second-highest in the majors behind Colorado’s minus-158.

The pitching staff now has the highest ERA in baseball at 5.75, barely ahead of Colorado’s 5.74.

The Red Sox are starting rookie right-hander Hunter Dobbins, who’s posted a 3.62 ERA in six games. He’s allowed two earned runs or fewer in four starts, and one or fewer in three.

In a modest sample size, left-handers are batting .333/.344/.619 against Dobbins and right-handers are batting .239/.301/.284.

The Red Sox appointed right-hander Cooper Criswell as their 27th man.

For the Orioles

Jackson Holliday 2B
Adley Rutschman C
Gunnar Henderson SS
Ramón Urías 3B
Ryan O’Hearn LF
Ryan Mountcastle DH
Cedric Mullins CF
Heston Kjerstad RF
Emmanuel Rivera 1B

Zach Eflin RHP

For the Red Sox

Jarren Duran LF
Rafael Devers DH
Wilyer Abreu RF
Carlos Narváez C
Nick Sogard 3B
Trevor Story SS
Abraham Toro 1B
David Hamilton 2B
Ceddanne Rafaela CF

Hunter Dobbins RHP