The top end talent is about the same. Mike Trout is about as good as Mickey Mantle or Ty Cobb. The worst players have gotten a lot better. The big jump in talent happened in the 1960s through integration. Expansion kept things in check for a while but the leagues haven't expanded for 25 years.
This I could see as possible, but I think teams want a "throw" day in the middle for practice. In the playoffs they shorten rotations and get rid of the "throw" day in between starts.