The Quality of Opposition Factor in the AL Cy Young Race

The AL Cy Young race has gotten pretty interesting. A month ago, Max Scherzer looked like a near lock, with his glistening 19-1 record and strong peripherals that supported the idea that he’d pitched like an ace this year. However, he’s gone 1-2 with a 4.66 ERA in his last five starts, perhaps opening the door for voters to take a closer look at all the candidates. And when they’re investigating, they just may find that the difference in quality of competition is a pretty significant factor this year.

For example, let’s look at the competition effect for Scherzer and Chris Sale. On first glance, you might think that there wouldn’t be a huge difference here, since both pitch in the AL Central and face a lot of common opponents. However, breaking down their starts by opposition reveals some striking differences. The following table lists their opponents in common first, then the teams that they faced that the other did not.

Opponent	Scherzer	Sale
Cleveland	4	4
Houston	2	2
Kansas City	4	3
Minnesota	2	2
New York Mets	1	1
New York Yankees	1	2
Oakland	2	2
Tampa Bay	2	2
Texas	1	2
Toronto	1	1
Seattle	1	1
–	–	–
Opponent	Scherzer	Sale
Chicago White Sox	5	0
Boston	2	0
Baltimore	2	0
Philadelphia	1	0
–	–	–
Opponent	Scherzer	Sale
Detroit	0	5
Anaheim	0	2

Among the teams in common, there aren’t many major differences. Scherzer got one extra start against the Royals, and Sale drew the Rangers one more time, but by and large, they basically matched up pretty similarly in teams that both pitched against. However, when it comes to the teams that one faced and the other did not, the story gets a lot different.

Both Scherzer and Sale have managed to draw five starts during the series in which their teams play each other. For Scherzer, that means five starts against the worst offense in the American League, as the White Sox have scored just 3.7 runs per game this year; for Sale, that means five starts against the Tigers and their 5.0 runs per game offense. This is one of the hidden advantages of pitching on a good team that inflates a pitcher’s W-L record: not only do you get the benefit of run support in helping decisions swing your way, but you never have to face your own offense, lowering your overall quality of competition at the same time.

Nowhere is this don’t-pitch-against-teammates divide larger than with Scherzer and Sale, as Sale essentially was selected out of facing the most feeble AL line-up, while Scherzer wasn’t forced to have a single confrontation with Miguel Cabrera or Prince Fielder this year. Having good hitters on your team doesn’t only get you more runs when you’re pitching, but makes it less likely that you’re going to give up runs, since that’s fewer good hitters you have to face yourself.

For the record, Sale was absolutely brilliant against the Tigers this year, giving up just 10 runs in those five starts, and throwing 39 innings in the process, so it will be tempting for some to wave away this difference as only theoretical, since all those extra starts against Detroit didn’t drag down Sale’s numbers. But by doing that, we’re marginalizing the very best performances Sale had all season, where he shut down an elite line-up and nearly averaged a complete game each time out. We should not just ignore Sale’s dominance against tough competition because he managed to overcome it rather than get beaten down by an offense that regularly beat down lesser pitchers.

For reference, here are the seven pitchers who currently have an RA9-WAR of between +5.5 and +6.5 — using RA9 instead of FIP because this is the pool that voters will likely consider — and the average runs scored by their opponents, per Baseball Reference’s calculations:

Pitcher	Opponents RA9
Chris Sale	4.54
Yu Darvish	4.46
Hisashi Iwakuma	4.42
James Shields	4.36
Max Scherzer	4.30
Bartolo Colon	4.29
Anibal Sanchez	4.27

Not surprisingly, we see the two Detroit pitchers near the bottom, with the Oakland A’s — 4th in the majors in runs per game — represented at about the same level, while the pitchers on teams with less effective offenses have each faced teams that have averaged about two-tenths of a run more per game.

This isn’t a large enough factor to be the deciding reason to pick one AL Cy young candidate over another, but the reality is that this race is really about splitting hairs, at least for voters who won’t put much or any weight on win-loss record. These guys have all pitched well this season, and there isn’t a huge separation between the pitchers at the top of the pack. There are a variety of candidates with arguments in their favor, and I wouldn’t say that Sale should win simply because he drew five starts against the Tigers.

It should be a factor, though. This is basically the same thing as a park effect, and it’s pretty well established at this point that a pitcher who posts a 3.00 ERA in Texas was more valuable than a pitcher who put up the same number in San Diego. We could essentially lump this difference in with park factors and refer to them in total as degree of difficulty, since opposing hitter quality affects the value of a raw number in a similar way to a park effect.

In a close race, this isn’t something that should be overlooked. And this year, it is a close race, even with Scherzer being the only pitcher to notch 20 wins. Sale and his 11-13 record are unlikely to get serious consideration, but he’s had a great season, especially once you factor in the schedule he’s had to face.