The World Series champions lost their 10th straight game and brawled with the Rays during an 8-5 defeat Sunday.
Rays pinch-hitter Sean Rodriguez connected for a tiebreaking, three-run homer in the seventh. Later in the inning, Yunel Escobar hit a two-run double and then took third on defensive indifference, setting off the fracas.
"There were some words exchanged," Red Sox manager John Farrell said. "We're down five in the seventh, so it's somewhat a gray area when you shut down the running game."
"Yunel is going to do some things that might be a little unpredictable, so that's what precipitated it," said Farrell, who formerly managed Escobar in Toronto.
Farrell admitted that Boston's slide may have also "boiled over a little bit."
Escobar, Rodriguez and Boston's Jonny Gomes were all ejected.
Rays manager Joe Maddon didn't quite agree with Farrell's assessment of baseball's unwritten rules.
"Last year in the playoffs, they had a 8-2 lead in the eighth when (Jacoby) Ellsbury led off with a single and then stole second base," Maddon said, correctly recalling what happened in the division series opener. "I think that was a little more egregious than their interpretation of what happened today."
"Before you start screaming about any of that, just understand what happened just last year, and also understand in this ballpark, five-run leads can evaporate very quickly," he said.
This is Boston's longest losing streak since an 11-game slump from June 8-19, 1994.
The Red Sox have been outscored 52-24 over their last 10 games. World Series MVP David Ortiz is hitting .118 and has no RBIs in that span.
"The effort is there," Red Sox second baseman Dustin Pedroia said. "The performance is not. So, we got to be better. It starts tomorrow."
Boston will try to end the drought on Monday afternoon when it plays at Atlanta.
Xander Bogaerts hit a two-run single with two outs in the Boston ninth off Josh Lueke. Grant Balfour got his ninth save by retiring Pedroia on a grounder.
Gomes pulled Boston even at 3 with a two-run, pinch-hit homer in the seventh off Joel Peralta (2-3).
After Craig Breslow (2-1) walked pinch-hitter Desmond Jennings and gave up Evan Longoria's single to start the seventh, Rodriguez gave the Rays a 6-3 advantage.
Escobar doubled and easily took third without a throw on the first pitch to Jose Molina.
Escobar got into a yelling match with the Boston dugout and had to be restrained just before both benches and bullpens emptied. The sides gathered around third base for a short session that mostly involved pushing and shoving.
"I'm not concerned about the bag at all," said Gomes, who sprinted into the fray from left field. "Yelling at my dugout, pointing at my dugout and taking your helmet off and basically challenging our dugout, I have a problem with that."
Escobar issued a statement through the Rays, saying that "as far as I'm concerned, it's over."
"They took offense to what we thought was fine," Rays third base coach Tom Foley said. "They called him out and he talked back to them and the next thing you know, benches cleared."
Longoria hit a leadoff homer and Logan Forsythe had an RBI single as the Rays took a 2-1 lead in the fourth.
Wil Myers made it 3-1 on a run-scoring grounder in the fifth.
Brandon Workman, recalled from Triple-A Pawtucket before the game, gave up three runs and five hits over five innings in his first big league start this season. He made three relief appearances with Boston earlier this year before being optioned to Pawtucket on April 8.
Rays starter Jake Odorizzi allowed one run and four hits in six innings.
Boston put 1B Mike Napoli on the 15-day disabled list with a sprained finger on his left hand. ... Rays RHP Jeremy Hellickson (arthroscopic right elbow surgery) threw batting practice and is set to pitch in a simulated game Wednesday. He expects to return before the All-Star break. ... Tampa Bay 2B Ben Zobrist (dislocated left thumb) hit against Hellickson and hopes to come off the disabled list next weekend. ... Farrell said Ortiz will play first base at least once in the two-game interleague series against the Braves.