If I am not mistaken Carroll Dial is the last player in baseball history to win 20 or more games in five consecutive minor league seasons. I also seem to recall that his complete record was listed in one of SABR’s minor league history books. At the moment all of my reference books are packed away; otherwise I would look up his record for you.
Once you learn his minor league stops (as I recall he played in the last 40s to the late 50s in the southwest around Texas, Arizona and maybe Oklahoma and California), you could try and borrow those city newspapers on interlibrary loan. It is time consuming but you would really get the complete picture that way.
