247 Sports just created a Transfer Portal ranking list. I'm not sure how they're going to relate it to overall class grades, if at all, but they are definitely paying attention to it. Here's the article introducing it:

https://247sports.com/Article/College-football-transfer-rankings-128478942/

And then here's the actual transfer portal page:

https://247sports.com/Season/2019-Football/TransferPortal/

Relevant Ohio State takeaways are that Justin Fields is the #1 transfer player, Tate Martell is #10, and Keandre Jones is #34.