Monday afternoon the Red Sox looked like a team that had enjoyed its long Memorial Day weekend and wasn’t quite dialed in.

There was a routine double play ball that wasn’t turned because the middle infielders were lined up too deep. There was a shallow fly ball that wasn’t thrown in quickly or accurately, allowing a runner to score from third on a sacrifice fly. Then there was the bases-loaded, one-out opportunity that the Red Sox let slip away.

These weren’t catastrophic errors, but all proved costly, especially against a Baltimore Orioles team that pounced on every inch the Red Sox gave away.

The Red Sox dropped Monday’s series opener in Baltimore 11-3, with the Orioles seizing control with a five-run fourth inning in which they loaded the bases with no outs and cashed in with back-to-back extra-base hits to deep left field. Kyle Stowers ripped a two-run double before Cedric Mullins broke things open with a two-run triple, and the Orioles kept piling on from there.

“They drove the ball all over the place,” Red Sox manager Alex Cora said. “That’s what they do, it’s like a fast break offense, they get into swing mode and they hit the ball hard and it was a tough one today.”

With the loss, the Red Sox fall to 0-4 against their division rival on the season.

Baltimore took an early lead in the second inning after Jordan Westburg drove in Colton Cowser with an RBI double. Cowser had just grounded into what should have been a routine double play, but Romy Gonzalez and Vaughn Grissom weren’t able to turn the play, putting Cowser at first and in position to score when Westburg lined one into the left-center gap.

Then in the third Adley Rutschman hit a fly ball to center that probably shouldn’t have been deep enough to score the runner from third, but Ceddanne Rafaela seemed caught off guard and wasn’t able to get the ball in fast enough, allowing Jorge Mateo to score on the sacrifice fly to make it 2-0.

The Red Sox had a golden opportunity of their own in the fourth, loading the bases with one out, but Dominic Smith and Rafaela struck out to end the threat. Both strikeouts were tough breaks for Boston, with Smith getting rung up on a called strike three that appeared to be out of the zone for ball four while Rafaela argued he made contact on his swinging third strike, which ended up in the dirt and could have been ruled a foul ball.

Compared to how the Orioles handled a similar situation moments later, the contrast was striking.

Immediately after the Red Sox squandered their opportunity, Baltimore loaded the bases after Ryan Mountcastle doubled, Cowser reached on an error by Grissom and Westburg walked. That quickly led to Stowers’ and Mullins’ big hits, and Mateo added a sacrifice fly to make it 7-0.

Red Sox starter Cooper Criswell, who came into the game with a 2.86 ERA, ultimately endured his worst start of the season with seven runs (six earned) allowed over four innings. He gave up six hits and one walk while recording just two strikeouts.

Right-hander Brad Keller, who signed with the Red Sox over the weekend after being designated for assignment last week by the Chicago White Sox, made his team debut and allowed four runs over four innings. All four runs came in the seventh inning thanks to an RBI double by Rutschman, an RBI single by Mountcastle and a two-run single by Stowers.

Stowers finished 3 for 4 with four RBI and a run, and Mountcastle was 3 for 5 with an RBI and two runs scored.

Boston’s bats did eventually get going in the eighth, but by that point it was too little, too late. The Red Sox loaded the bases with no outs after Orioles reliever Thyago Vieira walked three straight batters before Gonzalez cleared the bases with a three-run triple. Viera then walked a fourth batter before the Orioles went to left-hander Cionel Perez to get things back under control. He recorded three quick outs and the Red Sox never threatened again.

The Red Sox (27-27) will look to bounce back Tuesday night, with Brayan Bello (5-2, 4.04) set to face off against Grayson Rodriguez (5-1, 3.20). First pitch is scheduled for 6:35 p.m.