Conversation so far:
How did Walter O'Malley die?
Walter O'Malley died of congestive heart failure on August 9, 1979
Where did Walter O'Malley die?
Walter O'Malley died at Methodist Hospital in Rochester
Where was Walter O'Malley buried?
Walter O'Malley was buried at Holy Cross Cemetery in Culver City, California
Did Walter O'Malley have any children?
Walter O'Malley's children were Therese O'Malley Seidler and Peter O'Malley
What did Walter O'Malley do on the council?
Walter O'Malley became President and chief stockholder of Dodgers and moved the team to Los Angeles.
Did Walter O'Malley receive any awards?
Walter O'Malley won the Sporting News Executive of the Year Award in 1955
When was Walter O'Malley inducted?
Walter O'Malley was inducted into the Baseball Hall of Fame on July 27, 2008
What was Walter O'Malley legacy?
Walter O'Malley's legacy is that of changing the mindset of a league that for a long time had had the St. Louis Cardinals as its southernmost and western most team.

Question: How did he change the mindset?
Self-contained rewrite: How did Walter O'Malley change the mindset of the league?