This is not to say that there are no other candidates worthy of consideration.
Jon Lester has pieced together an outstanding season, but his campaign is likely hindered by the fact that it has been split between Boston and Oakland. White Sox lefty Chris Sale has also excelled, but he missed a month's worth of starts due to an arm injury early in the year and does not boast the same innings total as the others. Max Scherzer, Phil Hughes and David Price all merit a look, but the balloting should be a two-horse race in the end.
The season is not over, but the body of work is only one start from completion for Hernandez and Kluber. The Seattle right-hander is scheduled to take the mound against the Angels on Sunday, while Cleveland's workhorse is in line to start against Tampa Bay on Friday. When Hernandez allowed eight runs in 4 2/3 innings on Tuesday, he heightened Kluber's chances of an award-season upset.
Picking between Hernandez and Kluber could come down to the voter's statistical preference. Kluber boasts more wins (17-9) than Hernandez (14-6), but the Indians starter also has more losses. Looking at the ERA column, Hernandez (2.34) has the slight edge over Kluber (2.53). They have worked nearly the same amount of innings (230 2/3 for Hernandez and 227 2/3 innings for Kluber) in 33 starts apiece.
Shifting to more advanced metrics, Kluber currently ranks first in the AL in Fangraphs.com's version of WAR (7.0), while Hernandez (6.0) comes in at fourth, behind Hughes and Lester. When it comes to FIP (Fielding Indendent Pitching), which is based on home runs, walks and hit batsmen (things under a pitcher's control), Kluber has a 2.38 mark compared to 2.60 for Hernandez. That is a slim margin, but it is nearly the same gap as the difference in ERA for the pitchers.
Kluber has piled up 258 strikeouts against 49 walks, while Hernandez has tallied 241 strikeouts against 46 walks. Their strikeout-to-walk ratios (5.24 for Hernandez and 5.27 for Kluber) are nearly identical. Hernandez (0.94) does have the edge in WHIP on Kluber (1.10). Opposing batters have hit .233 (.629 OPS) against Kluber, but just .201 (.556) off Hernandez.
When it matters
Given how close Hernandez and Kluber are in terms of overall stats, an AL Cy Young Award voter will want to strip back a few layers to perhaps find a separator. Both the Mariners and Indians were involved in postseason chases until the final week of the regular season, so the pitchers' respective performances down the stretch might sway some ballots.
In the second half, Kluber was clearly the better of the two pitchers.
In 13 second-half outings to date, Kluber has gone 8-3 with a 1.88 ERA, 1.84 FIP and 0.97 WHIP. The right-hander has piled up 116 strikeouts against only 17 walks in 96 innings in that span, earning a 3.7 WAR rating, according to Fangraphs. He is 4-1 with a 2.57 ERA so far in September. Simply put, when the Tribe needed him most, Kluber elevated his game to another level.
For the Mariners, Hernandez has gone 3-4 with a 2.71 ERA in 13 second-half starts, though it is fair to note that Tuesday's disaster in Toronto skewed the stats. Still, the right-hander has turned in a 3.57 FIP, 1.00 WHIP and posted a 1.1 WAR since the All-Star break. That is still a solid showing, but it falls well short of what Kluber did in the same time period.
That said, Hernandez (2.50 ERA, 5.0 WAR) was better than Kluber (3.01 ERA, 3.3 WAR) in the first half.
Hernandez has also performed better against top-tier competition. Facing teams with a winning record this season (18 of 33 starts), Seattle's ace has gone 9-4 with a 2.50 ERA. He has gone 4-2 with a 2.54 ERA in nine starts against the AL's top five offenses (in terms of OPS). Kluber has gone 7-7 with a 2.67 ERA in 17 starts against teams with a winning record and 5-5 with a 3.20 ERA in 12 games against the AL's top five lineups.
The primary argument over putting too much stock in a pitcher's win total is that there are so many factors that are out of his control. The man on the mound can only throw the pitch. He has no say in what his team's defense or offense does that night. That is one reason why Hernandez took home the AL Cy Young Award in 2010 with a 13-12 record.
One thing that should be strongly considered for Kluber's AL Cy Young Award case this year is the defense he had behind him. Cleveland currently has the most errors in the AL, and the club's overall UZR (minus 70.9) is the worst in the league, according to Fangraphs. The Mariners, meanwhile, ranks sixth in the league in UZR (8.9) and Defensive Runs Saved.
There is also the fact that Hernandez pitches roughly half his games in Seattle's Safeco Park, which has been the most pitcher-friendly park in the AL this season. Progressive Field in Cleveland has also favored pitchers in 2014, but not to the same degree. Hernandez has gone 9-3 with a 2.12 ERA in 16 home starts, while Kluber has gone 8-6 with a 2.49 in 17 home outings.
In terms of run support, both pitchers have been hindered this season.
In Kluber's 16 starts that resulted in a loss or no-decision, the Tribe's lineup has produced 2.6 runs of support on average. The righty has a 2.31 ERA in his seven no-decisions this year. Similarly, Hernandez has received 2.7 runs of support in the 19 outings that resulted in a loss or no-decision. He has posted a 1.88 ERA in 13 no-decisions.
The AL Cy Young Award race remains too close to call.
If voters appreciate higher performance with postseason implications, Kluber might be their guy. If the voter likes ERA or history (Hernandez set a Major League record this year with 16 straight starts with at least seven innings and no more than two earned runs allowed), then maybe King Felix will be their pick.
If they are unable to decide between the two, maybe the voters will toss more votes Lester's way.
Every year, another element that is often discussed is what the player in question meant to his team. If neither the Indians or Mariners make the playoffs, some voters might think that issue is rendered moot. One quick way to show what Hernandez and Kluber meant for their respective teams, though, is to examine how the rest of the rotation did without them.
After removing Kluber's starts, the Indians' rotation went a combined 31-45 with a 4.32 ERA and a 1.36 WHIP this season. If the same is done with Hernandez and Seattle's starting staff, the result is a 46-49 record, a 3.92 ERA and a 1.27 WHIP for the Mariners' rotation. Both pitchers are critical to their clubs, but Kluber was arguably more important for Cleveland's ability to hang in the Wild Card race.
The only thing that is clear right now is that the AL Cy Young Award race took an unexpected turn this year.