Two days after making four errors in a 7-4 loss to the Cubs, the 13-12 Sox made four more errors against the Birds.
Three of the miscues came in one ugly top of the eighth, leading to three unearned runs.
Then, in the bottom of the eighth inning, Hanley Ramirez raced into second for an attempted double, not knowing Andrew Benintendi was still on the bag. Benintendi was tagged out and Boston's only rally of the night was short-circuited.
"Defensively, those are plays that are routine plays," said Red Sox manager John Farrell. "We're better than that. We've got to clean it up. It's a matter of anticipating the play before it's hit to you, whether it's a ground ball on the front end of a double play, whether it's understanding where baserunners are with a ball to the outfield, throwing the ball accurately as best possible.
"We're in a tough stretch defensively, far beyond what our capabilities are. We need to clean it up."
It has been a disjointed start to the season for the Red Sox, for sure. The offense has struggled to find an identity following the retirement of David Ortiz. Strong pitching performances by Chris Sale and Rick Porcello have been wasted.
And of late, proper fundamentals have eluded the Red Sox.
"What did we make, four errors? We've got to play better," said Red Sox second baseman Dustin Pedroia.
The baserunning gaffe by Ramirez seemed to be a lapse in concentration.
"I don't throw my teammates under the bus. It's my fault. That's it. I should have paid attention," said Ramirez.
"I saw the ball hit to left and I stopped at second," Benintendi said. "Obviously it's pretty surprising when you have two guys on the same base on your team so I was pretty surprised."
Benintendi wasn't at fault on the bases, but he did make one of the errors in the eighth, a wild throw home in which the runners were able to advance.
"It happens," Benintendi said. "It's baseball. It's going to happen probably again so all we can do is forget about it and worry about tomorrow."
The Red Sox will continue to get their early work in on fundamentals, but mental sharpness is equally important.
"The work is consistent as far as their daily and defensive routines," said Farrell. "It's a matter, to me, of making routine plays, and that goes along with anticipating what's taking place in the moment."
"It's human beings playing the game," said Porcello. "It's not robots. I mean, things are going to happen. A lot of times in this game when bad things happen it seems like a couple of things happen. So it's just kind of a funk that we're in and we've got to keep grinding and go out there and play everyday, and play hard and do what we can to correct those mistakes."
Ian Browne has covered the Red Sox for MLB.com since 2002. Follow him on Twitter @IanMBrowne and Facebook. This story was not subject to the approval of Major League Baseball or its clubs.