How could you call Meyer a "C" prospect, the guy hits 98 MPH as a starter and looks to have 3 plus pitches (not to mention size, good minor league results etc)? He was widely considered the 2nd best prospect heading into 2013 of the Nats farm class.
Meyer is clearly the best pitching prospect the Twins have and ranks somewhere between Hicks and Arcia but ahead of Rosario and Gibson, you wouldn't call those guys C prospects right??
Entering the 2012 season, BP ranked him 5th overall among the Nationals prospect, giving him 3 stars, which is a C prospect. BA ranked him 6th overall. And I don't see a lot in his numbers last year to have changed that opinion of him. I won't dicker between calling him a C+ or a B-, and I hope he's a C prospect with some upside, but a K/9 or 9 in High-A isn't exactly other-worldly stuff, no matter what his velocity.
I don't know that I would rank him in the same area you would. I'm also far from sure he'll be a top 50 prospect, or even top 100. But I'll admit, I'm far from an expert on the status of minor leaguers.