Eric Karabell calls Iwakuma his fantasy MVP among pitchers, but that's factoring in Iwakuma's relatively low average draft position. Eric's also right about this: Max Scherzer will probably win the award easily thanks to his sterling 21-3 record.
But whether Scherzer should be a lock is no longer such a sure thing.
Iwakuma ranks third in the AL in ERA (just behind the 2.64 marks of Bartolo Colon and Anibal Sanchez, both of whom have pitched far fewer innings), second to James Shields in innings pitched, second to Scherzer in opponents' OBP, third to Yu Darvish and Scherzer in batting average allowed and fourth in strikeout/walk ratio behind David Price, Chris Sale and Felix Hernandez.
In terms of Baseball-Reference WAR, however, it's not a two-pitcher race but a three-pitcher one:
Sale: 7.2 WAR (11-13, 2.97 ERA)
Iwakuma: 7.0 WAR (14-6, 2.66 ERA)
Scherzer: 6.7 WAR (21-3, 2.90 ERA)
The raw totals are close: Sale has allowed 77 runs in 209 innings, Iwakuma has allowed 69 in 219 2/3 and Scherzer has allowed 73 in 214 1/3. The statistical edge Sale and Scherzer have over Iwakuma is strikeouts -- 240 for Scherzer, 221 for Sale, 185 for Iwakuma.
(For the record, Iwakuma is rated much lower via FanGraphs WAR, which focuses on strikeouts, walks and home runs as opposed to actual run prevention. Scherzer, however, has pitched slightly worse with runners on base, or at least had worse results, than Iwakuma. For example, Iwakuma has allowed 25 home runs, but 19 have been solo shots. He's allowed a .228 average with the bases empty but .184 with runners in scoring position. Scherzer has allowed a .186 average with the bases empty versus .223 with runners in scoring position.)
One thing I like to look at is starts allowing two runs or fewer. You should win most of those starts; allow three and it's more of a 50-50 proposition; allow four or more, and you rarely win (only three pitchers have won at least four games this year when they allowed four-plus runs and only five, including Scherzer, have won three).
Record when allowing two runs or fewer:
Scherzer: 20 starts, 15-1, four no-decisions, 1.61 ERA
Sale: 14 starts, 9-3, two no-decisions, 0.98 ERA
Iwakuma: 20 starts, 12-1, seven no-decisions, 0.97 ERA
Iwakuma has pitched better than Scherzer in his good starts yet has three fewer wins. In fact, he's had four no-decisions when allowing zero runs. (All three pitchers have had seven starts allowing four runs or more.)
So yes, Scherzer has had better run support. Really, you can dissect this a lot of ways and all three are pretty even. But I suspect if you put Scherzer on the Mariners, we wouldn't be talking about a landslide Cy Young vote.
(For the record, I'd probably go Scherzer, Iwakuma, Sale, Darvish and Hernandez on my five-pitcher ballot. But maybe that's the Mariners fan in me not trying to be biased.)