By the end of his career, Felix Hernandez could possibly be in the discussion of "Greatest Pitcher of All Time". So many want to attribute that to Sandy Koufax, who was undoubtedly one of the greatest ever, but Felix has already enjoyed a more consistent career, and in the American League where teams feature better hitters.
There just have not been many pitchers with the sheer arsenal that Felix has available to him. The guy throws four seamers, two seamers, sliders, cutters, a wicked curve, and the best change up in the majors. At his current pace and consistency, he is going to be remembered as one of the greatest ever. If not the best ever, then top five.