He has literally built teams like Inter Milan and Man City.
At Inter Milan, he won 3 Serie A titles and laid the foundation of the modern day Inter Milan. It was his team that Mourinho joined that later went on to win the treble in 2010. He made that team.
At Man City, he won them their first Premier League title. It was his team that showed the world that Man United and Sir Alex Ferguson’s dominance can be broken. Later, Pellegrini and Guardiola reaped the rewards of his hard work.
For Italy, he took them from their worst ever position to becoming European Champions.
Roberto Mancini is a genius!