I do love high K/9 pitchers, who doesn't?... but when you look at a guy like Mark Buehrle, you have to consider him even with his low K/9 since he has a good command and excellent BB/9. He has a 3.82 career ERA over 16 SEASONS in which most of them he posted 3+, 4+ and even 5+ WAR numbers; and not to mention that he has been durable. In my book it is called consistency. I love consistency and durability regardless the stuff behind, reason why I like Lester, Shields, Buehrle, Papelbon, etc.
Look, He is 36 YO and he is under 4 ERA these days. He is probably one of the most underestimated pitchers ever. Bring me 4 Buehrles' career numbers pitchers and I sign them anyday.
Porcello's best WAR number is 2.8 through 6 seasons LOL!. Buherle posted 4 WAR in his second year of service, so... comparing him with Porcello just because both have low K/9 (Buehrle even below) is stupid.