Peters was actually being developed at LT prior to partway through last season, and was moved to RT after Williams got hurt and proved to be a bust, not to mention after Gandy proved to be a solid but unspectacular LT.
And as for Peters' ability, I'll wait until the real season starts, when they start watching game film and gameplanning for opponents. Not that I think he played poorly this pre-season (while Bennie Anderson has looked like garbage).