SEATTLE – Shaky lately at the plate and on the mound, the Boston Red Sox had problems in the field Monday that extended their longest losing streak of the season.

The Red Sox committed two key errors and the Seattle Mariners took advantage in a 4-1 win that handed Boston its seventh loss in a row.

“I think they are tired,” Red Sox Manager Bobby Valentine said of his players.

The Red Sox have dropped all seven games on their West Coast trip and have been outscored 58-16.

Clay Buchholz (11-5) went seven innings, giving up three earned runs and six hits while walking one and striking out eight.

Seattle scored all its runs in the fourth inning.

“Clay gave us the start we needed today. We scored first and I thought that was going to be it, we were going to snap out of it,” Boston catcher Ryan Lavarnway said. “But we can’t allow what happened in that inning to happen.”

Buchholz got in trouble in the fourth after Franklin Gutierrez beat out an infield single. He walked Kyle Seager and, on back-to-back pitches, gave up RBI singles by John Jaso and Justin Smoak to right that put Seattle ahead 2-1.

The Red Sox fell apart after that.

Eric Thames lifted a shallow fly ball to center fielder Jacoby Ellsbury and Jaso tagged up, broke for home and then stopped. Ellsbury’s throw bounced away from Lavarnway, however, and Jaso restarted and scored.

“I wish they had given me that error,” Lavarnway said. “Jacoby is trying to get that guy out. He’s doing exactly what he should have and I played it into an in-between hop. I need to go out and smother that ball — absolutely need to keep it in front of me.”

Miguel Olivo singled and Carlos Peguero hit what looked like a double-play grounder to shortstop Jose Iglesias. But the ball slipped in Iglesias’ hand, preventing a force at second, and he threw too late to first for an error that let Smoak score.

Valentine said Iglesias “was just being too quick, lost the handle.”

“We made the miscues that gave them two runs and that’s all she wrote,” he said.

Buchholz became the first Boston starter in four games to reach the fifth inning.

“Given the fact that we’re not really playing good baseball right now, not finding a way to win in all aspects of the game, it’s pretty tough,” he said.

Seattle’s Jason Vargas (14-9) pitched seven solid innings. Tom Wilhelmsen worked the ninth for his 23rd save in 26 opportunities.

The Mariners have won 10 of their last 12 games at Safeco Field.

The Red Sox scored a two-out run in the first. Dustin Pedroia had a ground-rule double for the 1,000th hit in his sixth full season, and Cody Ross singled.

 

NOTES: Pedroia has matched his season high with a 14-game hitting streak. He has had three hitting streaks this season of 13 games or more. … Boston DH David Ortiz has played one game since July 18 because of his two stints on the disabled list for a strained Achilles, but General Manager Ben Cherington expects the slugger back before the end of the season. “That’s our hope,” he said.