Consider the numbers.
Never won a Cy, nor an MVP
Sure, he led the league in Ks 11 times - but he led the league in walks 8 times.
Sure, he is the all-time best at preventing hits (6.6 h/9) - but its what's on the scoreboard that matters, right?
And he was a good number 2 or 3 for a very long time. A 112 ERA+. Twice led the league in ERA - but he had 7 seasons where his ERA was worse than the league average.
He won a lot of ballgames - 324.
And he lost 292.
Never led the league in wins - but he led it in losses once.
His teams sucked a lot - so its hard to hang it all on him - but you wonder, if they'd had a better #1 - maybe they'd have won more games....