SEATTLE (AP) - After their 4-0 loss to the Baltimore Orioles on Thursday night, the Seattle Mariners were left with a three-game losing streak and a state of confusion.
A critical first-inning play went against them after a lengthy replay review halted their momentum. And they still don't know why.
The real difference in the Orioles' victory was a three-run home run by Delmon Young in the third and a dominant eight-inning pitching gem by Wei-Yin Chen.
Chen (11-3) scattered five singles, walked one and struck out three. But it was his defensive effort in the opening inning that set the tone and sparked all the confusion.
James Jones walked to open the inning then stole second, the rookie's 20th of the season.
After a groundout, Robinson Cano dribbled a ball in front of the plate. Chen scooped and flipped it with his glove to catcher Caleb Joseph, who tagged Jones as he slid in head first.
''They actually practice that play in spring but it's one of those things people think you're killing time with pitchers,'' Orioles manager Buck Showalter said. ''But it came into play today.''
Mariners manager Lloyd McClendon protested the call but it was crew chief Fieldin Culbreth who initiated a review to determine if Joseph illegally blocked the plate. According to the new rules, the runner must be given a clear path to the plate.
After a review of 3:45, the original call was confirmed.
''I was going on contact and his foot was there in the way,'' Jones said. ''I didn't understand the rules, if I could run through him or I didn't know what to do but he was definitely in front of that plate.''
Joseph said he's ''pretty clear on the rules.''
''You try to catch it and make the tag,'' he said. ''The last thing in my mind is where you are position-wise. But that's an important aspect because of the new rules. We got it right tonight. We got it wrong about a month or so ago so it feels good to get it right this time.''
McClendon still isn't so sure.
''I can't go out and argue after the decision's been made,'' he said. ''I'm just a little puzzled. He didn't have the ball, his foot was in front of the plate, he caught the ball and he dropped (his knee). To me, that's blocking the plate.''
Asked if he thought Joseph was blocking the plate before he had the ball, Jones said, ''I couldn't tell, the play was going so fast, I just knew before the ball got to him he was there.''
Showalter said, ''that was a little bit of a momentum change there. Then he (Chen) showed how to get people out after that.''
Chen, who has won his past four starts, has 11 wins, tying him for third-most in the American League. On the road, Chen is 6-1 with a 3.94 ERA in nine starts.
Darren O'Day finished with a routine ninth inning.
It was Baltimore's eighth shutout. The Mariners have been shut out 12 times, tying Tampa Bay for the most in the American League.
Hisashi Iwakuma (8-5), who had won his previous three decisions, lost for the first time since June 25. He went seven innings, allowing four runs and seven hits. He struck out five without a walk.
Iwakuma, who had just two three-ball counts, has not walked a batter in a club-record five straight starts, a span of 35 2-3 innings. He is second in club history in walk-less innings behind Cliff Lee's 38, set in June 2010.
Iwakuma has 33 strikeouts against no walks in those five starts.
The Orioles began their four-run third with singles by John Flaherty, Joseph and Nick Markakis.
Markakis' single drove in one run and on the next pitch Young hit his fourth homer. It was the Orioles' 123rd of the season, tying Toronto for the most in the majors.
Young said he wasn't thinking home run ''just something to get us the runner in from third.''
Iwakuma said his shoulder was flying open at the beginning of the game ''and I was able to make adjustments at the end. But it was too late after that slider up in the zone.''
Dustin Ackley of the Mariners had a single in the second to give him a seven-game hitting streak and push his July average to .373.
NOTES: In addition to the acquisition of DH Kendrys Morales from the Twins before the game, Seattle also added two players from Triple-A Tacoma to the roster. Jesus Montero was called up for a second stint and started at DH. Chris Taylor started at short in his first major league game and singled in the fifth. When he called his parents in Virginia Beach to tell them the news, Taylor said, ''it was tough to hold it together. That moment is something you're never going to forget. Talking to them on the phone, telling them the news, hearing their voices, how excited they were, it's just an indescribable feeling.'' To make room, the club sent RHP Taijuan Walker back to Tacoma and placed INF Willie Bloomquist (right knee contusion) on the 15-day DL. ... The Orioles acquired INF Jimmy Paredes from Kansas City for cash considerations. He will report to the minors.