But figuring out how to hold the lead in the late innings remains a dilemma.
For the second consecutive game, and the third time on the six-game road trip, they squandered a lead in the eighth inning and dropped a 5-4 decision to the Blue Jays before 39,052 at Rogers Centre.
A two-run rally in the seventh and a three-run burst in the eighth stunned the Mariners, who lost their third straight in the four-game series, and returned home for the final week of the regular season still needing two victories to have a winning year.
"On this road trip, we put ourselves in position to win a lot of games, probably 5-and-1 if we get out of the eighth inning," manager Don Wakamatsu said. "But we had three games on this road trip with eighth-inning struggles. You obviously can't do that."
Seattle (80-76) is now 56-11 when leading after seven innings, and for the first time in 181 games -- dating to Aug. 13-15, 2008 -- Ichiro Suzuki went hitless for the second consecutive game.
Much more recently, Rowland-Smith was in cruise control entering the seventh inning on Sunday, having retired 15 of the first 16 batters he faced and 19 of 21 before Vernon Wells singled to left-center with one out.
Randy Ruiz followed with a double, putting runners on second and third, and Rowland-Smith found himself in trouble for the first time all afternoon. A sacrifice fly ended the lefty's shutout bid and a single past shortstop Josh Wilson, who should have made the play, chopped the second run off Seattle's three-run lead.
The play was ruled a hit, but everyone in the visiting dugout knew otherwise.
"It easily could have been the last out of the inning," Wakamatsu said.
Wilson agreed, saying he misplayed the ball.
"I just missed it, there is nothing more to say," he said. "It had a lot of topspin and went over my glove, but I just whiffed on it. I should have made the play. It cost us a run, and eventually helped cost us the game."
Designated hitter Mike Sweeney got one of the runs back with his eighth homer of the season leading off the eighth inning, but the Jays scored three in the bottom of the inning off Rowland-Smith and Miguel Batista to take the lead.
"I felt good after the seventh inning, but I just ran out of gas in the eighth," Rowland-Smith said. "I left a changeup up on [John] McDonald, and he hit it [for a double)] That's a guy I have to get out."
Jose Bautista followed with a run-scoring single and Rowland-Smith walked Aaron Hill.
The sometimes erratic veteran struck out the first two batters he faced and went ahead on the count 1-and-2 to pinch-hitter Adam Lind. The batter who hit two late home runs on Saturday afternoon to spark the Jays' come-from-behind win, singled to center to tie the game and Rod Barajas followed with a go-ahead double to left-center.
The Mariners have sorely missed right-handed reliever Sean White, who has been sidelined since Aug. 28 with tendinitis in his right shoulder.
That has caused Wakamatsu to play a different hand in the late innings.
"It is forcing guys like [Shawn] Kelley, who is young, and Batista, who has had inconsistent work, to pitch in those [late-inning] situations," he said. "But they still have to get it done."
After stranding six runners in scoring position in Saturday's one-run loss in extra innings, the Mariners advanced only one runner to second base in the series finale.
Four solo home runs were the extent of the Mariners offense.
The clouts included back-to-back jacks by Kenji Johjima and Matt Tuiasosopo in the fifth inning. Center fielder Franklin Gutierrez also hit a home run in the fifth.
Tuiasosopo's first career big league home run tied a club record. He became the 21st player this season to hit at least one homer, matching the record previously shared by the 1983 and '98 teams.
Rookies Adam Moore and Michael Saunders are the only position players currently on the roster who have not hit a home run with the Mariners.
"I knew I hit it well," Tuiasosopo said. "I had been reading [in the team notes package] that one of us had to hit a homer to tie the record and I told Saunders that now he has to get on board."
Blue Jays starter Brian Tallet regrouped after the Tuiasosopo blast and retired the next two batters before Gutierrez unloaded his 18th home run of the season -- a line drive that cleared the fence in left-center.
"We had the four home runs, but nothing much other than that," Wakamatsu said. "When a guy is pitching like Rowland-Smith was out there, you have to be able to tack on some runs with that."
And then figure out a way to get to closer David Aardsma.
"I want to get out there and help this team any way I can," he said. "Row was pitching a great game and that one inning ... he's mowing them down with no problem and it happened so quick."
Aardsma said he hadn't started to warm up, but he was thinking ahead.
"When Miguel came in and struck out the first two guys, I'm thinking, 'All right, he's going to strike out the side.'
"I was studying the hitters who I might be facing [in the ninth]," he added. "Three guys plus another guy, maybe. Today I was focusing on Lind and [Lyle] Overbay in case they wanted to pinch-hit for Ruiz or Millar."
But for the third time in the past four games on this trip, there was no lead for Aardsma to protect in the ninth inning.
Jim Street is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.