I don't think it's just those three. They were the first but not the only. Last year they found Tepera and Adam, and this year doubled down on Tepera and added Chafin. Plus ancillary guys like Winkler and Brothers who were actually pretty successful in limited roles early in the year (before getting blown up when pushed into everyday duty). The Cubs pretty likely belong in the club of teams who can build a pen on the fly. Like hell, it's still been okay since the trade deadline. Now maybe that's less about the investments in technology and more about the change to a portfolio style "bring in a bunch of interesting guys and it'll eventually work out" approach? But I do believe it's both. It won't truly be proven though until we see the randos accentuated with some fireballers pumped out by the player development team. Reports from Iowa and Tenn make it sound like that's imminent, but we do need to see it.