Let's say you have 100 white pitchers, 100 black pitchers, and 100 latino pitchers. You want to select the very best 50 pitchers. At first, you decide you want to select the best 50 white pitchers and exclude the blacks and latinos. That would give you one level of quality. You got the 50 best out of 100.(50th percentile)
Now, when you include the 100 blacks and 100 latinos, you would be selecting the best 50 out of 300, or the 83rd percentile.
Is it possible that the 50 best players out of the 300 are the same 50 from the all white pool? Yes. Is it probable? No. If one black or latino pitcher makes your squad of 50, by default, you improved the quality of pitching, because one inferior white player was replaced by one previously excluded black or latino player with better skills.
But, you're talking exclusively about pitching. Think maybe having other positions integrated might drop batting averages? Think about Willie Mays' over the shoulder catches, that would likely have fallen in during the all-white era. Think about the single robbing Ozzie Smith at short.
I'll never take anything away from the Babe, but comparing raw statistics without a look at contributing factors is an exercise in futility.
I recently saw an article in which Blacks were complaining because they make up about the same percentage of baseball players as of the general population, (around 12%).
Adding another 12% to the mix would make a difference but not a great one. Other factors would probalby be more significant.
I think the percentage of Black pitchers is even smaller.
No doubt that Ozzie was a great infielder, (taking nothing away from him) but his national TV back flips got him a lot more publicity than others who were as good or even better with the glove.
Bill Mazeroski finally got into the Hall a few years ago via the "Old-times" committee -- long overdue and if the players instead of writers voted, he would have made it on his first year of eligibility. Maz stopped far more hits than Ozzie ever did and the Pirates lead the league in double plays for something like 12 of the the 17 years Maz played with whatever SS they had. His hands were so fast and no one could take him off his feet.
The combination of Mazeroski being very quiet, non-flashy kind of guy coupled with his 7th game-9th inning game ending HR beating the mighty media darling 1960 NY Yankees worked against him in getting the spot he desreved in the Hall of Fame for 30 years. (I damn well gurantee that if the situations were reversed and Maz hit that HR for the Yankees, he would have been in on the 1st ballot. That's the way it works)
At lest they finally made it right. Some folks get the publicity they deserve, and others don't, but don't confuse publicity with contributions.