Well Jack Johnson, Sammy Langford, Georges Carpentier, Charley Burley and Gene Tunney all fought in 1922 or later.... It is opinion, but The Ring seems a bit slack with their research if your hypothesis is true...
You could present a reasonable argument for Langford being at #1 though, so it does kind of undermine things a wee bit.
I cant see how he can be out of anybodys top 4 at 160,his style turned me off,but you cant argue with his record,I saw him once he was working the corner of Carlos Herrera against Maurice Hope,he didnt look very big ,in track bottoms and top ,tall but slim,his weight looked to be all in his top half.