Stats not on BR

1888:
California League (pitching) batting and fielding

1889:
California League

 1890:
California League standings
Indiana State standings
New York State standings
Pennsylvania State standings
Tri-State standings
Western Interstate standings
Western New York standings

has stats: Western Association  pitching  standings
California League

1891:
Wisconsin State League
California League

1892:
With Stats:
New England League

1896:
Canadian League

1900:
California League

1907:

Amateur:

1892:

Chicago City League
New York Amateur League

missing extra categories:

1912 Western Canada League

1916 Eastern League

Western Canada site has Western Canada League stats ex. 1909

1926 Pacific Coast League

California State League

1900 Western League E

1901 Three-I e

1903 Western League e

1904 Missouri Valley League pitching/fielding newspaper considers them to be inaccurate
1905 Iowa State League pitching

1906 Tri-State League 4 Three-I e

1909 Texas League everything 

1910 Southern Association everything

1914 Western Canada League fielding only not on BR

1915 Central League 4

1922 Michigan-Ontario batting/standings (split-standings)

1928 Nebraska State League pitching

1928 PCL batting (most legible) w/ split standings batting (more complete) pitching

1929 PCL Batting pitching pitching (more legible) batting (more legible - w/ split standings)

1940 Tar-Heel batting .241+

https://sabr.org/research/patric-doyle-professional-baseball-player-database-research-files/

Patric Doyle archives

1949 Provincial League https://sabr.app.box.com/s/aql3nrr4icazzam7afcrb42r4fngo5dy/file/757088566172

also better than the stats on Christian Trudeau's site

ManDak