It might have been a "dead ball" era, but the fields were not "manicured" like they are today.
Way more funny boucnes and as stated, "oven mitts" often is attributed to higher batting averages. That, and the vast outfields especially between the power alleys and centerfield.
Then you have the Astro-turf era. Players like Ozzie Smith actually palyed a "shallow" LF and were able to get to balls they wouldn't have gotten to on grass.
Most of the Astro-turf stadiums were multi-use. As was Tiger Stadium until the Silverdome was built. Come late August/Septmeber, many a game showed a worn field where a NFL game was played.
I cannot think of a multi-use stadium currently being used for MLB and NFL games.
I know some of the older posters know what I am talking about. Either watching an NFL game where you could see where the bases were, or vice versa.
I certainly believe domed stadiums have had an impact. No wind means a lot to a flyball or pop out.