Back in the first half of last season it was tough to imagine Hisashi Iwakuma having a year like this one. But with Felix Hernandez pretty much down for the count this final month Iwakuma stepped his game up a notch even from the stellar first five months of the season. As a result he ends his year with a 23-inning scoreless stretch to go with a 14-6 record 2.66 earned run average and 219 2/3 innings pitched.

That latter stat — the innings total — seems astounding given the quality that went along with it. Especially given all the early struggles he had with between-outings fatigue last year as he returned from shoulder troubles in 2011 and adjusted to a new life and game in the United States.

But Iwakuma committed himself to building up strength and endurance this past winter and it showed all year cluminating with another eight scoreless innings tonight in a 6-0 win over the Kansas City Royals. Mike Zunino hit a pair of mammoth homers in addition to catching Iwakuma through his final stint of the season while Michael Saunders also went deep.

“First and foremost like I said in spring training one of my goals was to stay healthy through the long course of the season and stay in the rotation for a long time during the season” Iwakuma said through interpreter Antony Suzuki. “I accomplished that goal with 200-plus innings so I’m very happy with that.”

So are the Mariners. Some of the advanced value statistics like FanGraphs WAR (Wins Above Replacement) still have Hernandez ahead of Iwakuma when it comes to overall worth this season. But that’s largely due to that stat’s Fielding Independent Pitching (FIP) component and its heavy reliance on strikeout totals.

Baseball Reference WAR has a runs-allowed component to its WAR measurement and lists Iwakuma as one of the top-three pitchers in baseball.

It’s tough to declare Hernandez as Seattle’s top pitcher of 2013 when he barely pitched the final month. Making it through an entire year carries huge weight with teams and the players who ply their trade on them and in that regard you’ll privately find little dissent among the Mariners as to who the team’s best pitcher was this time around.

Iwakuma says he doesn’t really know why he got stronger as September rolled along — piling up season high eight-inning outings in back-to-back starts. He does know that he found better upper-and-lower-body balance towards the latter part of the season and it caused less stress on his shoulder and elbow.

The fans at Safeco Field saluted Iwakuma with a standing ovation as he headed off the mound following his ninth strikeout of the game in the eighth inning.

“I’m very happy very grateful at the same time” Iwakuma said. “I’ve never experienced that to be honest with you that’s the first time I’ve got through it. So it was quite impressive.”

Mariners manager Eric Wedge and his staff deserve credit for how they nurtured Iwakuma along through the early part of last season. And then again this year for how they managed his arm through early blister troubles and then all through the season in order to pace the pitcher through his first complete big league campaign in a rotation.

“It’s just been a lot of fun to watch him have a great season” Wedge said. “And a lot of fun to watch him continue to progress over here. He does the work he pays attention to the game prepares himself well and he handles everything in a grand fashion too out there. I appreciate that.”