Frank wasn't on steroids, but...
1) Frank was a freak of nature and the franchise GOAT.
2) The back half of his career he averaged 99 games, which is when his body caught up with him. Imagine what he and Griffey could have done compared to known roiders, who were able to soldier on.
Re: 50s, 60s, 70s...
Guys throw harder, run faster, jump higher, etc., there's just more strain on the human body. Adam Engel would have been a fucking god and led the Go-Go Sox to a World Series. Giolito would destroy that era. Lopez pumping 100 mph fastballs? Forget about it.
*This is assuming you can just teleport them directly into the past.
Remember how rare it was to see a 100 MPH pitch? Now every team has several guys.