Watching the pressors of coach McVay whenever goff/qb questions are mentioned, he seems to always take a moment to mention Mannion in a positive light. Its not a universal thing. He doesn't do it with all groupings and players. In fact, I think he mentioned Murray once and Mannion multiple times in a positive light. To me, the way he said it showed interest. If Sean Mannion was my client, Coach McVay would stay on the jury following jury questioning.
Remember context as well, this is a guy that had a front row seat to watching RGIII get drafted in 2012, named to the pro bowl and rookie of the year. Two years later McVay is elevated to OC and plays a central role as OC in leading the skins offense from 25th overall to 10th not with the high draft pick but the 3rd rounder that was kind of an afterthought when he joined the team in Cousins.
I think that experience and whatever he is seeing with Mannion leads me to speculate that Coach McVay holds Mannion in high regard. Hopefully we never find out because Goff is the next coming of Joe Montana . . .