Jay Jaffe's JAWS averages Career WAR and 7 year peak WAR
Grove 86.1
Randy Johnson 81.3
Spahn 75.8
Carlton 72.2
Plank 71.1
Glavine 62.4
Average HoF 61.6
Kershaw 58.8
Newhouser 57.6
Koufax 47.4
Pitching WAR for best 7 seasons (not consecutive)
Grove 65.6
Johnson 61.5
Carlton 54.3
Newhouser 52.6
Spahn 51.4
Plank 51.1
Average HoF 50.0
Kershaw 49.7
Koufax 46.0
Glavine 44.1
https://www.baseball-reference.com/leaders/jaws_P.shtml
Unless the criteria is 4 consecutive years, I don't see the argument that Koufax is the discussion of the greatest all time.