Umm, Newcomb entered the year as a top 25 prospect and was supposed to be a potential mid-season boost to the rotation. Last year he pitched 136 innings over 3 levels (A, A+, AA) with an ERA of 2.38, a K/BB ratio of 2.2. The knock was he needed to improve his control and cut down on the walks.
This year in AA he has thrown 123 innings with an ERA of 4.10, and a K/BB ratio of 2.08. He is striking out fewer hitters and hasn't improved his walk rates much at all. In the midseason prospect rankings he has dropped outside the top 50, and I assume will be even lower this offseason.
If that's not flopping then I suppose we have dramatically different ideas of what succeeding entails.
Sims hasn't flopped, but only because he wasn't thought of very highly this past offseason anyways.