Rickey is well known for Jackie Robinson. What he influenced more was the minor league system he reintroduced in the 1920s. By the 1940s, nearly four in ten MLB players had been inside a Rickey Farm.
Branch Rickey was good at seeing what the problems were usually, and figuring a cheap solution until the money was around to make even MORE money. (Axiom: takes money to make money.) The Cards had a cash-poor franchise before 1920. They were smart to sell off assets (a ballpark) to fuel a cheaper way to get ahead. Renting for a spell – and locking that in for quite awhile – and building a franchise from the Midwestern corn-fed boys on up. Other teams saw the successes of this formula and mimicked the Rickey plan.