There are two possible scenarios I see playing out here: the Rams are being forthcoming and the elbow is as it was last season, they're just doing their best to manage it better. Or, worst case scenario, the elbow is not doing well and at some point Stafford needs to have surgery. The optimist in me feels like even if surgery is necessary, he'll come back at least close to full strength with significantly less pain.
We don't know what it is, tendonitis or otherwise. We do know that it's causing him some discomfort. To what degree? Only Stafford and the Rams know and that's all we're gonna get.