I guess I'm saying that I don't think the idea that Stevenson can't catch Robles as a prospect is one that I subscribe to. Prospect ratings are kind like star ratings in college football recruiting, to me. Once they get into the system, they don't really matter that much.
12/1 profile pic bet: if Stevenson ever passes Robles in a rankings update or full year list for Fangraphs, Baseball America, or MLB.com, before either of them loses their prospect status, you can pick my profile pic for 12 months. Otherwise, I pick yours for 1 month.
There is a 0% chance that Stevenson is ever thought of as a better prospect by any reputable source.
If you want a recent example - Michael Taylor vs. Billy Burns. Burns has had a really good full season in the majors, which is more than Michael Taylor ever had. But Burns was not close to MAT in prospect status. MAT peaked in top 50 lists.
And Robles is far beyond MAT, even if Andrew Stevenson is a little above Billy Burns.