https://www.quora.com/Why-did-the-Milwaukee-Brewers-move-to-the-National-League-and-then-the-Houston-Astros-move-to-the-American-League
This explains the Astros / Brewers moves
From what I've seen
Astros moved to the AL to balance out the AL/NL leagues (15 teams in each league)
Mlb wanted a Texas rivalry with Rangers and Astros
https://www.baseball-reference.com/leaders/leaders_salaries.shtml
Lots of Yankee players on this list
Harper might go to the top of the list with his next contract
Oct 18 1977
First World Series Memories
https://www.google.com/amp/s/www.newsday.com/amp/sports/baseball/yankees/oct-18-1977-reggie-jackson-hits-three-homers-in-world-series-clincher-to-become-mr-october-1.14521673