It's one single source you're using to base your determination. From the link you Posted:
Prospects FV change from season to season, making a conclusion based on such little information is silly. We acquired lottery tickets for expiring contracts hoping a few of them break out, it happens all the time. Nobody was giving up a 55-60 FV prospect with what we were selling.
Additionally, Giles averaged 1.8 WAR from '14-'17 yet you give 0.7 based on 30 innings this season so it fits your narrative.