Feel dirty for dumping on United's manager (again) in another thread, but wrt to the Rijkaard loosening the reins bit after inheriting a functional side:
Valdés - Played 10 games under Louis.
Oleguer - Promoted to the first team by Rijkaard.
Márquez - Bought by Rijkaard.
van Bronckhorst - Bought by Rijkaard.
Edmílson - Bought by Rijkaard.
Deco - Bought by Rijkaard.
van Bommel - Bought by Rijkaard.
Giuly - Bought by Rijkaard.
Ronaldinho - Bought by Rijkaard.
Eto'o - Bought by Rijkaard.
Belletti - Bought by Rijkaard.
Sylvinho - Bought by Rijkaard.
Motta - Got his debut under Carles Rexach and became an important player, played 10 games under Louis.
Iniesta - Played 5 games under Louis.
Larsson - Bought by Rijkaard.
The side Rijkaard inherited was far from functional and he had to purge 80% of the squad/ loan players (Rochemback, de Boer, Christanvel, Overmars, Kluivert, Enke, Enrique, Andersson, Reiziger, Garcia, Bonano, Cocu, Geovanni, Riquelme). It's wasn't a transition, but a complete revamp of the team. As for the playing style, the biggest credit goes to Michels and Cruyff dating backing to decades before Rijkaard was appointed because they set the template for the future.
PS: One player whose influence in underrated was Edgar Davids, who arrived on loan from Juventus. If not for him, maybe Rijkaard would have been fired, and maybe Xavi wouldn't have become the playmaker he became because too many defensive duties were being placed on him, and Davids' arrival allowed him to flourish as the team's prime mover. David might played a small role in creating the history of Barcelona and Spanish football by liberating Xavi.