Iwakuma gives Mariners a second true ace

Felix Hernandez has deservedly gotten most of the credit for the Seattle Mariners’ success this season, but he is not the only reason that fans in the Emerald City are on the brink of watching October baseball for the first time in 13 years. He's got a pretty good sidekick in the rotation, too.

Hisashi Iwakuma delivered another gem on Tuesday night, blanking the Philadelphia Phillies over eight innings with a season-high 11 strikeouts and no walks to lower his ERA to 2.57 this season.

When you come to the United States from Japan in the same offseason as Yu Darvish and you pitch in the same rotation as King Felix, it's easy to get overlooked. But the degree to which Iwakuma is underrated is almost a crime.

He is easily the most anonymous ace in baseball, and all the proof you need is in this list of qualified American League starters that have a lower ERA than Iwakuma (2.63) since his first MLB start on July 2, 2012:

Yup, that would be no one.

Iwakuma was an All-Star last season, but missed out on being selected to the game this year as he struggled through a rough four-week period in May and June during which he posted a 4.67 ERA over seven starts.

But since the calendar turned to July, he has produced a King Felix-like run, going 7-2 with a 1.63 ERA. The only American League pitcher with a lower ERA in that span is Corey Kluber (1.31) and no pitcher in the majors has more wins than Iwakuma since July 1.

He has gone at least seven innings in eight of those 10 starts, allowing more than two runs just once. Perhaps the most impressive statistic of this dominant stretch is this: 65 strikeouts, four walks.

That last number should come as no surprise to anyone who has watched Iwakuma this season. His control is approaching historic levels, as he now has a mere 12 walks in 147 innings. This rate of 0.73 walks per nine innings easily leads all major-league starters and puts him on pace to enter the record books.

Only two qualified American League pitchers in baseball history have posted a walk rate that low in a single season: Carlos Silva (0.43 in 2005) and Cy Young (0.69 in 1904).

Iwakuma doesn't have an overpowering fastball (averaging 90-91 mph) but he has incredible command of four pitches and a devastating splitter that is nearly unhittable. His combination of outstanding control, an above-average ability to generate grounders and a solid strikeout rate puts him in elite company.

The only other pitcher this season with a walk rate of less than four percent, a ground-ball rate of at least 50 percent and a strikeout rate of 20 percent or better is ... Mr. Clayton Kershaw. Otherwise known as the best pitcher in the world, the NL Cy Young favorite and legitimate candidate for the NL MVP award.

Despite his impressive resume, Iwakuma works in relatively anonymity, quietly mowing down lineups in the shadow of the King. He doesn't have a cool nickname or a devoted following of fans, but Iwakuma's consistent approach is a perfect complement to the utter dominance of a pitcher like Hernandez.

Seattle's offense has come alive during August (4.8 runs per game), but that hides the fact that they still have the lowest on-base percentage (.302) and OPS (.677) in the American League. And yet somehow the Mariners have the second-best run differential in the AL (+99) and are in position to make the playoffs for the first time since 2001.

It's hard to imagine where the Mariners would be without their dynamic duo of Iwakuma and Hernandez at the top of the rotation. The playoffs would certainly be a pipe dream. But thanks to the combination of baseball's most anonymous ace (Iwakuma) and most deserving ace (Hernandez), Seattle is now in prime position to give its fans something besides football to cheer about in October.

Katie Sharp blogs about the Yankees for SweetSpot network affiliate It's About the Money, Stupid, and can be followed on Twitter at @ktsharp.