It is true that the best of the Negro leagues would have succeeded in the Majors during this era. But you are making several erroneous assumptions, such as: A Negro league players success in the Negro leagues would have been essentially the same in the majors. This is not the case for some obvious reasons:
a) Ball Parks -- Negro league fields were in many cases minor league ball parks, which tends to favor the hitter and the home run.
b) Pitching -- Good pitching beats good hitting. As much as you will deny it, the quality of pitchers in the Negro leagues was not what it was in the Major Leagues. Best evidence of this is to take a look at after the color barrier was broken, how long did it take for black pitchers (yes there are exceptions) to really become dominant in the big leagues? And how many of these are there compared to other pitchers in the bigs?
c) Quality players -- Blacks represented about 8-10% of the population, Whites being the vast majority of the rest. Thus the Major leagues had a larger pool of talent to draw from. This cannot be proven, only surmised, but I would guess that depth of talent in the Major leagues was far deeper then that of the Negro leagues. Thus a major leaguer was playing against better talent, when taken across the board.
Sorry, but crying racism does not dilute the success of the white players, rather it over inflates the statistics of the black players.
Another curious aspect of ballpark sizes is that the shrinking ballparks have made triples somewhat more rare than they used to be. A guy named Chief Wilson holds the big-league record with 36 triples in a season (1912, when he played in cavernous Forbes Field in Pittsburgh). Nowadays, you usually find players leading the league with 10-15 triples in any given season.