SEATTLE -- Rangers manager Ron Washington has long enjoyed a reputation for being an expert on defense, especially in the infield, and he has been known to seethe at miscues.

He certainly was seething on Sunday afternoon, especially over one play in particular by part-time third baseman Matt Kata. Pitcher Robinson Tejeda wasn't too happy either.

Both saw it as the critical play on an afternoon in which the Rangers led 4-1 in the top of the fourth before unraveling in the bottom of the inning on their way to an 11-6 loss to the Seattle Mariners at Safeco Field.

"Today was one of the first times in a long time that we just fell apart," Washington said. "Tejeda did his job today. We just didn't help him defensively."

Victor Diaz, who has combined with Marlon Byrd to just about completely push Nelson Cruz out of the Rangers' outfield situation, hit two home runs and drove in five runs. But the Rangers still lost for the third time in four games to the Mariners and are now 6-15 against their American League West opponents this year.

Kata's misplay -- which was actually ruled a hit to Tejeda's great dismay -- was hardly the only thing that went wrong that inning. Tejeda made a couple of mistakes himself. But the bottom line is that the Mariners scored five runs that inning and it changed the entire afternoon.

The Mariners also added four runs in the sixth, when Byrd lost a fly ball in the sun and second baseman Ian Kinsler made his 12th error of the season.

"We lost that game on defensive miscues," Washington said. "Two innings cost us the game."

Tejeda, who was one out away from getting out of the fourth and continuing on to a well-pitched game, instead ended up giving up eight runs in 5 1/3 innings and is now 4-6 with a 6.28 ERA on the season.

That makes it a complete set for the current Rangers rotation. All five starters have an ERA of over 6.00.

"Today, I felt good," Tejeda said. "I also felt my delivery was good. I feel very good about the way I was throwing."

Diaz's first home run off Mariners starter Ryan Feierabend was a three-run shot in the top of the fourth that gave the Rangers a 4-1 lead. But it didn't stay that way for long.

Feierabend ultimately pitched 7 1/3 innings to get the victory, but Washington insisted that it would have been a completely different story if the Rangers could have kept the Mariners from scoring in the fourth.

Asked about Feierabend, Washington said: "To me he didn't have nothing. ... He did a good job, but he certainly wasn't fooling anybody. As far as I'm concerned, we had him up to close to 80 pitches [after four innings]. He wasn't going to be around much longer."

Raul Ibanez led off the Mariners fourth with a single, then Richie Sexson flied to deep right. Tejeda walked Ben Broussard, his first walk in the game, but Yuniesky Betancourt fouled out for the second out of the inning.

That brought up Willie Bloomquist, the Mariners' No. 8 hitter who entered the game hitting .205. Tejeda got ahead of him 1-2, and then tried to come inside with the fastball and hit him in the back to load the bases.

Then came the most-discussed play of the game.

Jamie Burke, the Mariners' backup catcher and No. 9 hitter, then hit a sharp grounder down the third-base line. Kata said he tried to get in front of it and go for the force at third. Washington said he should have backhanded it and gone for the out at first.

Kata couldn't quite get in front of it and ended up only knocking it down with his body, a play that was ruled an infield single. Kata has been platooning at third base with Ramon Vazquez while Hank Blalock is out, and this was only his sixth start this season. But Kata insisted he feel comfortable at the position, even though he had a two-error game there earlier this season against the Mariners.

"I tried to get around it and couldn't quite do that," Kata said. "That's a play that's got to be made. That was unfortunate. One of my strengths, I feel, is my glove, and that's a play that should be made."

Washington made that clear as well.

"[Tejeda] shouldn't have hit Bloomquist, but it happens," Washington said. "Then he came back and made a pitch, and we don't make the play. If we make the play, we're talking about, [Tejeda] is going pretty good and the score is still 4-1.

"I'm not trying to single him out, but that's a play that should be made. There's nothing difficult about it."

Tejeda admitted that he was upset that the official scorer ruled it a hit.

"That was one of the things that made me sick," Tejeda said. "It was a routine ground ball. It was not a hard play to make. In that situation we have to make the play. But there's nothing you can do about it. He was trying to make the play."

Before he could compose himself, Tejeda walked Ichiro Suzuki to force in a run and then gave up a three-run double to Jose Lopez that gave the Mariners a 6-4 lead.

Washington put it all back on Kata.

"If we make that play, we're out of the inning and it's still 4-1," Washington said.