2015 NL cy young

Avg opponents runs (from bb ref)
Arrieta: 4.20
Kershaw: 4.22
Greinke: 4.24

soo, not exactly a huge difference, but not sure how thoroughly those numbers are calculated.

"He made a big leap last year, but how do you go from a terrible pitcher from 24-26--literally terrible--to historically great at 29?"

It's not totally unusual. I think the big thing is that usually the pitcher gains control of a certain pitch that is nearly unhittable and then they can combine it with experience on how to setup hitters. Arrieta has definitely taken it to another level.

Mike Scott and Dave Stewart are a couple of guys that came to mind for seemingly came out of nowhere to become one of the best pitchers in the game. (Obviously Scott's pitch he learned was considered controversial by some.) Schilling had been pretty inconsistent and at age 29-30 pretty much became dominant.

http://www.baseball-reference.com/players/s/scottmi03.shtml

http://www.baseball-reference.com/players/s/stewada01.shtml

the cubs changed his mechanics and positioning on the mound also

That's what I was looking for, a tangible explanation. Scott's a good comparison, and the explanation is that he developed what was, for a year or two anyway, an all-but-unhittable split-finger. I don't know if Stewart's a good comparison. With him, I think it was more that he ended up in the right place at the right time; he was a good pitcher and a workhorse, but in the four years he won 20, his ERA was in the 3.00s three times, and his WHIPs were in the 1.200-1.300 range. He was never dominant. Schilling was great as a 25-year-old, and he struck out 300 at 30 and 300 again at 31; he just couldn't stay healthy until he got to Arizona.

an all-but-unhittable spitter

I was thinking about Stewart as A's got him off waivers, he was literally on baseball's garbage pile. Not many times you get a guy off waivers that ends up anchoring your rotation like he did for that club back then.

I do see your comparison in broad outline--reclamation project, emerges at age 30 as the ace of a mini-dynasty. It's more a question of magnitude. Stewart wasn't all that different a pitcher before and after the A's got him:

1978-85 (Dodgers/Rangers/Phillies): 3.96 ERA, 1.356 WHIP, 1.55 K/BB
1987-90 (his four 20-win seasons): 3.20 ERA, 1.241 WHIP, 1.96 K/BB

('86 was split between the Phillies and A's, and I'm too lazy at the moment to manually add in those partial seasons.)

Obviously a better pitcher, and credit to the A's for seeing what other teams missed. But Arrieta's turnaround is much, much more dramatic.

2010-12 (Orioles): 5.33 ERA, 1.451 WHIP, 1.79 K/BB
2014-15 (Cubs): 2.08 ERA, 0.915 WHIP, 3.53 K/BB

(Same split-season in the middle of that.)

Arrieta's 2014-15 K/BB ratio should read 4.53.

Someone asked if Scherzer has had the best season that will not get a single point in the Cy voting.

he'll probably get a few. Cy ballot has 5 spots, and by fWAR he's in 3rd (leapfrogging Greinke last night) and 4th by bWAR.

but yeah, crazy to have a season with 2 no-hitters (and a 1-hitter and a 2-hitter), strong performances otherwise, and not even be in the conversation

his previous start he had a no hitter going into the eighth inning.