Pitching for the Mariners isn't the same as pitching for the offense-laden Tigers or Rangers, so one has to look much deeper than the 14-6 record put up by the 32-year-old from Japan.
Iwakuma posted a 2.66 ERA in 219 2/3 innings, both numbers better than his Cy Young competitors, Max Scherzer of the Tigers and Yu Darvish of the Rangers.
He outperformed Hernandez on his own team -- no easy feat in itself -- with a remarkably consistent campaign. He quietly established himself as one of the AL's premier hurlers in his first full year in the Mariners' rotation, after a decade of dominance in Japan.
Iwakuma posted impressive numbers across the board, finishing second in the AL in WHIP (a club record 1.006), third in ERA, innings and opponents' batting average (.222), fourth in strikeout-to-walk ratio (4.40) and quality starts (23) and fifth in opponents' OPS (.630).
Iwakuma had the highest WAR of any AL pitcher at 7.0, with Scherzer third at 6.7 and Darvish fifth at 5.8. While Scherzer and Darvish put up superior strikeout numbers, Iwakuma's wicked splitter kept hitters off balance and his command was outstanding. As a result, his strikeout-to-walk ratio of 4.40 was also ahead of Scherzer (4.29) and Darvish (3.46).
But the argument for Iwakuma needs to also include what he did for a club that went 71-91 and posted the lowest batting average in the AL at .237 and was 12th in runs scored. That lack of offensive support resulted in 13 no-decisions for Iwakuma, despite posting a 2.86 ERA in those games.
The 6-foot-3 right-hander became the second pitcher in Major League history to have five starts of at least six innings in which he recorded a no-decision despite not allowing an earned run. Roger Clemens endured the same fate in 2005 with the Astros.
Iwakuma went eight innings on six different occasions, but was just 2-0 with four no-decisions despite a 1.69 ERA in those games.
If just six of Iwakuma's 13 no-decisions had been wins, he'd be a 20-game winner and staring straight in the eyes of Scherzer's 21-3 season for the Tigers.
But the stoic veteran never gave in, no matter the situation or support. His opponents' batting average was .184 with runners in scoring position, and .111 with runners in scoring position and two outs.
Iwakuma, a three-time All-Star in Japan's Pacific League, earned his first AL All-Star berth and then got stronger as the season progressed. He closed out the year with a 4-0 mark and 1.62 ERA over his final eight starts.
His success wasn't just a product of pitcher-friendly Safeco Field, as he recorded the third-lowest road ERA in Mariners history at 2.45 and finished the year on a 25-inning scoreless streak on the road.
Iwakuma was the only pitcher in the Majors with two scoreless streaks of at least 20 innings, posting runs of 23 2/3 and 23 innings, respectively.
It all added up to a breakout season in the Majors for Iwakuma. But it was not all that surprising a feat for a pitcher who helped Japan win the 2009 World Baseball Classic and was MVP and Eiji Sawamura Award winner -- his country's equivalent of the Cy Young -- in a 21-4 season with a 1.87 ERA in 2008 for the Rakuten Eagles.