But those gains were offset by setbacks that led to a losing record for the third straight year of manager Eric Wedge's regime and fewer wins than the club achieved in 2012, with Wedge announcing in the closing days of the campaign that he would not return next year.
"We're a completely different team now than we were in Spring Training," Wedge said at season's end. "We're not that team anymore. We haven't been that team in a long time. With really turning it over and having all these young kids in the bullpen and rotation and from a position player standpoint, it's tough to go out and compete the way you want. But that's what they did. They competed and learned each and every day."
Expected offensive improvements from veteran outfielder Michael Morse and catcher Jesus Montero never materialized, injury woes again eliminated center fielder Franklin Gutierrez for much of the year, shortstop Brendan Ryan was benched and then traded in September after hitting below .200 for a second straight season and youngsters like Michael Saunders, Dustin Ackley and Justin Smoak had more ups and downs than hoped for as core players in the rebuilding plan.
The offense produced the most home runs of any Mariners club since 2000, but that didn't translate into an increase in scoring, and the team still ranked at the bottom of the American League in batting average.
With Hernandez and Iwakuma leading the way in All-Star seasons, the pitching staff kept the club in most games. Hernandez joined Detroit's Justin Verlander as the only active Major League pitchers with five straight seasons of 200 innings and 200 strikeouts. And Iwakuma was sensational in his first full season as a starter in the Majors as he posted better numbers than even Hernandez and was strong from start to finish, capping his year with 23 consecutive scoreless innings and one of the lowest ERAs in the league at 2.66.
But inconsistency in the back end of the rotation and in the bullpen proved troublesome. Seattle's relievers had the second-worst ERA in the AL, closer Tom Wilhelmsen lost his job in midseason and by year's end the group was relying on a number of youngsters with limited experience.
"We're all included in the team and we win together and we lose together," said Ibanez. "You know there was some disappointment on our part. I think we're a better team than we played this year."
A number of youngsters gained experience across the board as the midseason youth movement brought aboard a new middle infield with Miller and Franklin, a backstop of the future in Zunino, a promising setup man and closer combination of Yoervis Medina and Danny Farquhar and some eye-opening starting talent in Walker, Paxton, Brandon Maurer and Erasmo Ramirez.
Walker debuted with five innings with no earned runs and just two hits in Houston on Aug. 30 in Houston and Paxton allowed just one earned run in his first two starts, including six scoreless innings at St. Louis in his second start on Sept. 14, and finished up at 3-0 with 1.50 ERA in four outings.
The frustration of 2013 seemed to be about how close the club was to turning the corner, without quite getting there yet. The team set a franchise record for most extra-inning losses in a season and had the most walk-off defeats in the AL. It went 9-20 in one-run losses on the road and repeatedly seemed to just lack the one timely hit in a key situation needed to change a game, and ultimately, a frustrating season.
"We had that one big winning streak at one point," said Smoak. "We just need to maintain that attitude day in and day out. If you pitch and play good defense and score a few runs, we've got a chance to win a lot of ballgames. There were a lot of games we got walked off this year. There were a lot of games we lost in the other team's last at-bat. If we turn those around it's a different ballgame. It's something we'll all learn from and be ready for next year."
Record: 71-91, fourth in the AL West
Defining moment: The Mariners picked up four tough losses in a row in Cleveland in mid-May in a brutal series that kicked off an eight-game losing streak, dropping Seattle from 20-21 to 20-29 after it had just won big series against the A's and Yankees and seemed to be gaining some momentum. But two extra-inning losses and a couple bullpen implosions against the Indians proved tough to overcome as Seattle then got swept in a short series in Anaheim and lost twice to Texas. And the team never got closer than four games under .500 the rest of the way.
What went right: Hernandez and Iwakuma provided Seattle one of the premier one-two punches in baseball, both earning All-Star bids and pitching well throughout the year. … Looking to add some punch to the lineup, the club added some power hitters and moved the fences in at Safeco. And the Mariners wound up with their most home runs since 2000. … Ibanez was signed as a part-time player and veteran leader, but wound up providing a productive bat and led the team in home runs at age 41. … Seager again showed he's one of the bright young third basemen in the league with a second straight solid season at the hot corner. … Looking to the future, the club unveiled some extremely promising arms in late-season callups Walker and Paxton and also got a very solid year from Medina.
What went wrong: The team the Mariners broke camp with in April after a strong Spring Training never seemed to get off on the right foot. Gutierrez lasted just three weeks before going on the disabled list with a string of issues that wiped out most of his season, Morse got off to a torrid start but then fell off dramatically after the opening month and wound up being traded in August, Ryan and Ackley both hit around .200 for the first few months before losing their jobs and Montero didn't hit or defend well and was sent to the Minors and eventually suspended in the Biogenesis case. … The back end of the rotation struggled much of the year as veterans Joe Saunders, Aaron Harang and Jeremy Bonderman were inconsistent and injuries to youngsters Danny Hultzen and Ramirez limited or eliminated their ability to step in. … The bullpen didn't live up to expectations as Wilhelmsen struggled and lost his closer's job, Stephen Pryor got hurt and missed almost the entire season and hard-throwing Carter Capps couldn't find much consistency.
Biggest surprise: Farquhar began the season in Tacoma and was largely an unknown reliever obtained in the Ichiro Suzuki trade in July 2012. But the 5-foot-9 right-hander wound up as the Mariners closer by midseason after getting an early promotion to the bullpen and then showing such promise that he was called on to replace Wilhelmsen in early July. Despite only three games of Major League experience before this year, the 25-year-old proved to be poised and potent and was impressively consistent in save situations the final three months.
Hitter of the year: The Mariners traded for Morales to add a veteran bat in the middle of their lineup and the 30-year-old designated hitter delivered with a strong season at the plate. Morales led the team in batting average and RBIs and was a consistent producer with runners in scoring position.
Pitcher of the year: Iwakuma established himself not only as a valuable starter in his first full year in the Mariners rotation, but as an All-Star hurler and one of the premier right-handers in the AL. It's not easy to outshine Hernandez, but Iwakuma had superior numbers and stayed healthy and consistent through the entire campaign.
Rookie of the year: Miller stood out among a strong crop of first-year players as he stepped into the lineup in late June and provided an offensive spark as a leadoff hitter who could run, take the extra base and provide some occasional pop as he did with three two-homer games. While many of the rookies endured expected highs and lows, Miller remained pretty steady throughout his initial campaign and showed natural leadership at the critical middle-infield position.