No. 6: Roger Clemens, 1986
The first year where he really became Roger Clemens, and he goes out and wins a unanimous Cy Young Award and a MVP award (and World Series MVP if Buckner fields the grounder to first... let me stop before this tangent gets too long). Clemens' 1986 campaign was truly a masterclass from April to October, and he earned every single accolade that came his way because of it.
Clemens won his first Cy Young unanimously this year, on top of becoming MVP. He went 24-4, keeping an ERA of 2.48, allowing less than 1 walk or hit per inning pitched, and pitching to a tune of a 169 ERA+, good enough to lead the American League. Clemens accumulated 8.8 WAR for his 1986 campaign, and sits perfectly in the middle of this ranking. It's always tough to compare the value of pitchers to hitters, especially across different eras of baseball. However, I think Clemens coming in and asserting himself as the ace of the rotation at such a young age and showing the whole league how great of a pitcher he justified his spot here at #6.