IDK if a dedicated QB coach would add value.As you say, and also intimated on TKR podcast that Vallone is basically an OL coach in training - why bother with a TE coach at all?
If the philosophy under OC KC is TEs are just another blocker, go all the way and have OL Flaherty in charge of them.
Use that coaching spot for a dedicated QB coach to work with Wimsatt, AK, Surace etc.
Mario Verduzco- what did he achieve at Nebraska as QB coach? Not much.
Drew Mehringer- he was a QB in college and OC/QB coach at Rutgers. What did he do? Took out Laviano who had a nice season in 2015 in favor of Gio Rescigno. Huge blunder. In his famous goal line stand against Iowa, he had featherweight Tylin Oden in to try to punch it in.
IMO, the quality of the player and the schemes put in place by the OC matter much more than anything a dedicated QB coach can do for the QB.