This is an invaluable detailed reading of Adrianople and a useful corrective to the Osprey book - anyone wishing to go deeper into the debate would find much interesting material here:
Adrianople
Two points arise out of my own admittedly amateur research into this battle: where are the Saraceni foederate cavalry in the battle? Ammianus is always dismissive and reticent about Arab barbarians, and, also, in reference to the priest sent over to Valens with the two letters, I think I might have divined his identity but await further enlightenment from the scholars on this site! (p.s: I wonder if we should open a separate thread here?!)