First, the Twins aren't really notoriously slow. That perception came b/c of a flawed understanding of a study of prospects who were called up. Since the Twins were such a small market team, they'd use older prospects rather than get a FA to plug in. So they had some old rookies - Ford was 26, Koskie 25, Tommy Watkins gets included, Luiz Rodriguez etc. But they had a bunch of guys debut at 22 or younger - Mauer, Morneau, Rivas, Kubel, Durbin, Liriano, Casilla, Garza, Gomez, Revere, Young, Ramos etc. But even if you don't want to believe that, when Ryan came back he put Brad Steil in charge of the minor league development and you can say that Steil has been pretty strong with pushing prospects as a lot of the biggest names have done multiple levels each year.