MLB, post-Moneyball, shifting focus to player development

MLB seems to be entering a new era centered around using data and analytics to focus on player development. Even though "Moneyball" taught teams to be smarter in constructing their rosters, why did franchises struggle to develop their talent?

MLB seems to be entering a new era centered around using data and analytics to focus on player development. Even though "Moneyball" taught teams to be smarter in constructing their rosters, why did franchises struggle to develop their talent?