If the idea is to stay competitive, keep the window open, yada yada, i.e. the premise of this article, then yeah, the gains do need to be rather immediate. Sinking years of (MLB or MiLB) investment into players hoping to get passable MLB performance is what rebuilding teams do. If Manzardo never becomes anything more than a plodding 1B who hits the occasional HR, yep, it's a bad trade, because not only did you fail to capitalize on Civale's value at the time, but you've also continued to give away valuable playing time to Manzardo.
Saying Manzardo has done nothing to help Cleveland the last 2 seasons isn't the same as closing the book on his career. Joe Ryan is a terrible example here. Not only was he immediately inserted into the rotation post trade, he was, ya know, actually pretty good for an entire season+ before "settling," in 2023. Even that season, relative to his peers, Ryan was an average pitcher. Manzardo has been a bottom tier 1B since he came up.