There was also the first combined no-hitter in franchise history, with veteran Kevin Millwood combining with five relievers to blank the Dodgers on June 9.
On the flip side, the Mariners themselves were subject to a perfect game by Philip Humber of the White Sox on April 21, then tied a Major League record by striking out 20 times in a 5-4 loss to the Angels on Sept. 25.
And no, it wasn't always just about pitching, as the Mariners knocked out a 21-8 victory in Texas that stands as the second-highest scoring game in franchise history.
Ups and downs, highs and lows. Every team has them. But how far did this club come? As the campaign kicked off in Tokyo Stadium, Kyle Seager wasn't a starter, Michael Saunders was a huge question mark, Tom Wilhelmsen was merely one of several setup men in a rebuilding bullpen, nobody knew much about third-string catcher John Jaso and there were large concerns about a starting rotation beyond Hernandez.
Not all the questions got answered positively, as Seattle finished fourth in the American League West for the seventh time in the past nine years. But manager Eric Wedge talked from the start of building a foundation with this group, laying the groundwork with a young nucleus that indeed took a solid step forward in his second season.
Wedge isn't satisfied with just winning more games than the club had since 2009. His bar is ultimately set a lot higher than that, but he also knows that positive steps were taken and that some important pieces fell into place this year.
"When you talk about our young players, it's more about their progress," Wedge said. "We have so many young starters: We were starting six, seven, sometimes eight guys a night that are 25 or younger. And when you don't have that big bopper in the middle, these guys were kind of fending for themselves. As long as they keep getting better, that's the most important part of it.
"It takes time. You can't shortcut the process. There's no other way to get home than to do it the way we're doing."
Seager, 24, moved into the lineup the second day of the season after Mike Carp sprained his shoulder, and he quickly established himself as a clutch hitter and needed run producer in the middle of the order in his first full season in the Majors.
Saunders, 25, had hit just .196 in parts of three previous frustrating seasons in Seattle, but came to camp with renewed fire and improved batting approach, and -- after an injury to Franklin Gutierrez -- he emerged as a quality center fielder who can run and hit with some power.
Wilhelmsen, 28, continued his storybook ascent by becoming Seattle's closer in early June after Brandon League struggled, quickly establishing himself as an imposing force with his upper-90s heat and a wicked curveball at the back end of a bullpen flush with promising young power arms and some quality lefty specialists.
Jaso, 29, provided a surprisingly timely left-handed bat, leading the team in average and game-winning RBIs even while splitting time among the catching trio of rookie Jesus Montero and veteran Miguel Olivo.
And the rotation? Not only did Hernandez roll out another AL Cy Young Award-contending season that included a perfect game and an AL-leading five shutouts, but Jason Vargas cemented himself as a capable No. 2 starter as he posted career highs in wins and innings, Hisashi Iwakuma emerged in the second half as a quality veteran in his first season in the Majors, young Blake Beavan posted double-digit wins and rookie Erasmo Ramirez came on with some late-season flash to provide further hope for a franchise deep in pitching prospects in the Minor Leagues, as well.
Add in the expected continued development of young cornerstones Dustin Ackley and Montero, two of baseball's premier young prospects who just underwent their first full seasons in the big leagues, and there indeed are reasons to think 2012 was a needed step in the franchise's continued development.
"I think we're just learning how to win," Ackley said. "That's something we didn't do great in the first half, but in the second half, we proved to ourselves we can win any type of ballgame. It helps us to know we're capable of doing it and beating great teams like the Rangers and other clubs. Getting that confidence and belief you can do it is the biggest part.
"You don't really learn how to deal with it until you've been there. Everyone was in big situations this year, whether it was helping win a game in the ninth or whatever, and that's huge for us to go through that as a young team and get that experience. We've been in perfect games, no-hitters ... I don't think there's going to be anything new come our way here. With all we went through this season, it's pretty crazy."
Record: 75-87, fourth in AL West.
Defining moment: For a team building around its ace, there could be no greater moment than The King's perfect game on Aug. 15, when Hernandez made history against the Rays by recording 27 straight outs at Safeco Field. A season filled with ups and downs stood perfectly still that afternoon, as Hernandez zipped through nine flawless frames and took his place with just 22 previous pitchers in Major League history.
What went right: Hernandez and Vargas topped a rotation that again gave Seattle a chance to compete on a nightly basis, with Vargas stepping strongly into the No. 2 spot and providing career highs in wins and innings pitched. Iwakuma looked solid after joining the rotation in midseason, as well. ... A young bullpen proved an absolute strength with Wilhelmsen replacing League in June and quickly establishing himself as a shutdown closer. The Mariners discovered some excellent left-handed relievers in converted starter Charlie Furbush, Rule 5 Draft pick Lucas Luetge and reclamation project Oliver Perez, while hard-throwing rookie right-handers Stephen Pryor and Carter Capps showed promise for the future. ... Seager and Saunders had breakout years on both sides of the ball. Seager established himself as a quality third baseman and middle-of-the-order run producer, while Saunders was the surprise of the season as a solid-hitting center fielder who stepped nicely into the hole created by Franklin Gutierrez's injuries. ... Jaso proved to be a quality addition as a clutch-hitting left-hander, working well in a platoon situation with the 22-year-old Montero, as Seattle's offensive production took a big step forward at both catcher and designated hitter.
What went wrong: Wedge's experiment with putting Chone Figgins back in the leadoff role and dropping Ichiro Suzuki to third in the order never found any traction and was abandoned after several months, with Figgins benched and Ichiro eventually traded to the Yankees in July. ... Justin Smoak didn't have the step-up year the club expected, and Carp was hampered by injuries from Opening Day, leaving first base and left field as major question marks and greatly reducing some of the middle-of-the-order power Wedge had counted on. ... Gutierrez tore his oblique muscle early in Spring Training and missed several months, then got a concussion and sat out six more weeks shortly after his return, thus taking away one of the club's experienced right-handed bats and a Gold Glove-caliber center fielder. ... The club struggled to hit at home in the first few months, batting under .200 and getting off to a slow start at Safeco until ripping off a 15-1 streak there after the All-Star break. ... While Brendan Ryan and Ackley were superb defensively up the middle, Ryan hit below the Mendoza Line almost all year, and Ackley didn't have the big sophomore season most expected from the second overall pick in the 2009 First-Year Player Draft.
Biggest surprise: Trading Ichiro to the Yankees on July 23 caught nearly everyone off guard after the iconic Mariners right fielder quietly requested the chance to be dealt to a playoff-contending team for the final two months of his contract. Ichiro had spent the first 11 1/2 years of his Major League career with Seattle, but had seen his batting average and on-base percentage dip sharply the past two seasons. As he turns 39 this October, Ichiro faces an interesting decision next season as to his future in Major League Baseball, but the Mariners no longer are involved in that process after the two sides parted ways following 1,844 games and 2,533 hits in a Seattle uniform.