I agree the latter is far more plausible :)
According to one source (
http://www.btinternet.com/~mark.furnival/theodor.htm) "the boy was christened
Dietrich , a common name amongst the Germans of that era. In Late Latin, the name translated as Theodoricus and the boy grew up to become the man known to history as
Theodoric the Great."
I am not too sure about the relevance of the "late-latin" part, as Greek was the *lingua franca* of the
Easter Roman ("Byzantine") empire.
Spot-on,
Mike !