QB coach is an entry-level coaching position (after playing/GA). Brandon Doman. Brian Johnson. Jason Beck. Steve Sarkisian. Rick Neuheisel. I could go on.
Ty Detmer has 14 years experience as an NFL quarterback. He's from a coaching family. He has coached (albeit at a small high school) successfully. Brett Farve claims Ty taught him a ton about the position. Reputation in the football world as incredibly smart and great x's and o's guy with a great knowledge of the game. Unqualified endorsement from Lavell Edwards.
To have all that experience and be offered a position that you give to a 22 year old would be insulting if I were Ty. His cumulative experience qualifies him to be an OC.