Kind of doubt that Negro League baseball was on the same level as the major leagues by 1953, because the best Negro League players had already gone to the majors by then. It was six years, almost seven, after Jackie Robinson came to the Dodgers when Banks arrived with the Cubs in September 1953. The Negro Leagues would soon fade into history because their best players were swallowed up by "organized baseball."
Also, the other black player with the Cubs at the time was GENE Baker, NOT Glen Baker. Gene Baker, though he did not have a Hall of Fame career by any standard, did one thing Banks never did: he played on a world championship team (1960 Pirates).
When Banks came to the Monarchs in 1950 the Negro American League was still close enough to major league level play; the exodus really began in earnest around the time Banks went into military service. (The Negro National League folded around 1948.) What I read of the Negro American League tells me it became Pacific Coast League (the vintage PCL, that is) caliber by 1950 but began a decline around the time Banks went into the military and finally folded formally in 1958. The last Negro Leagues team still playing by the 1960s was the Indianapolis Clowns---about whom a good book could well be written.