RICHMOND, Va. — Eduardo Rodriguez had a second impressive outing Friday night for the Portland Sea Dogs.

The bullpen? Not so much.

Wilfredo Boscan allowed four runs in the seventh inning, Michael Almanzar committed a costly error at third base and the Richmond Flying Squirrels ralled for a 5-1 victory.

But as far as the Sea Dogs were concerned, what will be remembered was not the loss but the outing by Rodriguez, the 21-year-old acquired by the Boston Red Sox from the Baltimore Orioles for Andrew Miller at the trading deadline.

Rodriguez, who was 3-7 with a 4.79 ERA in 16 starts for Bowie this season before the trade, pitched six scoreless innings against Richmond, striking out nine and walking three, giving up three hits.

In his first start for Portland, Rodriguez worked 51/3 innings against Trenton, allowing two hits, one run, one walk and striking out seven to get the win.

“His starts have been very impressive,” said Portland Manager Billy McMillon. “Six innings tonight, no runs. He did a really good job of keeping us in the ballgame. Keeping their hitters off-balance with fastballs and good off-speed pitches.

“It’s not hard to see why he was (the No. 3) prospect in the Orioles’ system.”

Rodriguez, who was signed by Baltimore as a non-drafted free agent out of Venezuela in 2010, had a 10-7 record last season between Class A Frederick and Bowie in the Orioles’ organization.

“I feel good,” said Rodriguez. “I just do the same as I do with Baltimore but my pitches are way better now. I make the choice when I want to throw my pitches in certain counts, and that’s why I’m feeling much better.”

Before Friday night, Rodriguez had been 0-3 against Richmond.

“I try to be more consistent with my fastball, with my change-up, with my slider,” he said. “Throw different pitches in different counts. That’s what I do way better tonight.”

In the game between Eastern League division leaders, the Sea Dogs were without their leading hitter, infielder Sean Coyle, who sprained his right ankle in Thursday’s loss at Bowie.

Coyle is batting .309 with 13 homers and 55 RBI in 85 games.

“He’s day to day,” said McMillon, who added that Coyle hurt the ankle while stepping on first base legging out an infield single.

The Sea Dogs may have run themselves out of an opportunity in the second inning. David Chester was thrown out trying to stretch a single into a double to open the inning. After a groundout, Carson Blair doubled to left.

That was followed by walks to Jonathan Roof and Stefan Welch to load the bases but Ryan Dent popped up to end the inning.

Portland threatened again in the fourth, loading the bases with two outs, but again Dent couldn’t deliver, lining to deep center for the final out.

In the fifth, Almanzar rocketed a fastball from left-hander Ryan Bradley over the left-field wall to give the Sea Dogs a 1-0 lead.

Meanwhile, Rodriguez held the Flying Squirrels to one hit through the first four innings. But Richmond touched him for a pair of singles in the bottom of the fifth, and he loaded the bases before working his way out of trouble.

After Rodriguez left, the Squirrels roughed up Boscan. The error by Almanzar made the final three runs unearned.

Skyler Stromsmoe drove in Richmond’s first run with a single to center and with two outs, Mario Lisson drilled a 3-2 pitch from Boscan over the left-field wall for a three-run homer to make it 4-1.

Lisson had struck out three times against Rodriguez.

Richmond added its final run in the eighth on a two-out run-scoring single by Eliezer Zambrano en route to breaking an eight-game losing streak.

Portland has lost nine straight to Richmond.