I didn't look at the periferals and I agree that W/L is not the best measure of a pitchers value. Especially when they play on a perenial powerehouse like the Weaver era O's.
However, I saw those guys pitch dozens of times. They were "dominant". Sometimes talent transends generations and eras. Those four, along with guys like Gibson, Seaver, Marichel (sp), Blue, McClain, etc., would be very sucessful and likely as "dominant" if they were pitching now.
Just as Gale Sayers or Jim Brown would be in football ( where the players are bigger and faster now) or Wilt Chamberlain and Lew Alcindor (as examples) in basketball.