It was the second consecutive game Seattle pitchers surrendered 12 runs, and the third time in the past six games opponents have reached double figures.
The Angels started the scoring onslaught with 11 runs last Saturday, and veteran left-hander Cliff Lee has been the only starter since then to pitch well against American League West foes.
He held the Rangers to two ninth-inning runs in the four-game series opener on Monday night, a little rally that apparently lit a fuse in Texas' bat rack. Seattle was outscored, 31-6, in the final three games.
Unlike the other lopsided defeats, the latest was caused more by defensive mistakes than poor pitch location, although there was some of that as well from starter Ryan Rowland-Smith and reliever Brandon League.
"It's hard to tell the outcome of a ballgame if you don't make the defensive plays behind the pitcher," manager Don Wakamatsu said. "[There were] eight unearned runs on two ground balls that have to be made."
The first one, a potential inning-ending double-play grounder hit to second baseman Chone Figgins, skipped through him leading to a four-run Rangers outburst in the third frame.
Instead of being out of the inning and behind by one run, the Mariners were looking at a five-run deficit.
"That stuff is going to happen," Rowland-Smith said. "It's not like I'm sitting there blaming the entire game on that. The bottom line is you have to work through that and pitch around it."
The Mariners' second error of the game came in the sixth inning and triggered a five-run uprising that KO'd Rowland-Smith.
With two outs and one on, shortstop Josh Wilson let a chopper go under his glove for an error, and the next four Rangers batters drilled hits and produced the five runs.
"It went under my glove," Wilson said. "I just misplayed it."
The Mariners, meanwhile, are misplaying a season that was expected to be so much different. They are now a season-high 14 games under .500 (23-37) and a season-high 10 games behind in the AL West.
Most of that deficit is because they are now 7-21 against teams in their division.
"Losing is frustrating," Wilson said. "I don't know if the last three are any more frustrating than any other games we have lost. Losing games any time is not fun."
After being outscored, 27-6, in a three-game series sweep against the Angels at Safeco Field, the Mariners were outscored, 33-10, against the Rangers.
"I don't know if we dominated," Rangers manager Ron Washington said. "The past couple of games, we've scored a bunch of runs. I'm just concerned about the Texas Rangers really.
"Knowing the type of the guy that Don Wakamatsu is, he's going to stay on top of them until 162 games are over. You might see something different from Seattle by then."
The Mariners can only hope that some of the balls they start hitting fall in as often as the ones the Rangers hit during the final three games of the series.
"It seemed like a lot of balls they hit were finding holes," Wilson said. "We certainly hit a lot of balls hard the last two games that didn't find grass."
Wakamatsu was encouraged by the way Rowland-Smith handled the defensive lapses, saying: "After all the damage was done, he settled down a little bit and showed us more of what he did last year."
Rowland-Smith shared some of the same feelings, though his record dropped to 0-5.
"I walked away from this game, especially after that third, thinking, 'My stuff's good enough.' I felt confident. As the last couple of innings went on, it got better."
The bottom of the Mariners' lineup did most of the hitting in the latest setback. Left fielder Michael Saunders and Figgins each had two hits.
"Offensively, the story is the top the order. One through five was 0-for-17," Wakamatsu said.