just took a quick look (real quick) at '16, and the #s for Porello/verlander/Kluber were all close, (ERA, ERA+, WHIP) with Verlander and Kluber having having more Ks (but also more walks) than Verlander, Porcello's record of "22-4" was noticeably better and a real differentiator.
Porcello's CY win sort of reminds me of Bob Welch over Clemens in '90. IMO Clemens was the best pitcher in baseball that year, but its hard to ignore 27 wins.