Yep, Walsh's best, and yep, all these 3 are very good.
Mitchum was also great (and cryptic) in Man with the Gun and of course El Dorado is another one of his charismatic best.
But I think there is a great difference between Mann's way of creating characters with psychological undertones and the use of psychoanalytical patterns in Pursued.
And Distant Drums is in any case a western. A tough actioner. Quite different from Pursued.
I never understood how the studio employee Walsh could fit the author theory.