I agree entirely that we've had lots of players go from a small role to a bigger role successfully. What I am saying is that we don't have a lot of history of guys going from NO role to a solidified role in the rotation. Tanner (maybe entirely due to injury) had effectively no role this year. Just because we don't have a history of it, doesn't mean he can't contribute at some point.
This year - we have one player that went from out of the rotation to in the rotation. Trey Stewart. Many want him to transfer. (I don't.) The only examples I've found in the last ten years of someone that was not in the rotation (I define as 8 MPG minimum, and playing a majority of games where not injured) are Trey, Trevin Knell, Kolby Lee, and Jake Toolson. They all played way more than Tanner did this year their first year on the team. Two of those guys transferred! A third might this year.
In NO way do I think Pope can't develop talent, or that Tanner is a lost cause. I simply am saying that there is an extremely limited history of players going from benchwarmer to major contributor.