Found an incorrect 1890 player...
John Fitzgerald (fitzge006joh) real stats are incorrect, he import with no stat for 1890 but he have a line for 1891 which aren't his since 90 was his only season in the ML. They are the stats of John H. Fitzgerald (fitzge007joh) who played for Boston in 1891.
https://www.baseball-reference.com/p...itzgjo02.shtml
Edit: I can't check but maybe the 1891 John Fitzgerald is incorrect too since his stats are assigned to the wrong player...