Reason the deflector and indeed the rest of the ship looks weird is because it is the very low detail 2ft model that was absolutely never intended for 1080p resolution !
Yeah in SD you could often mistake it for the 6-footer if you didn't look too hard (such as in Q Who?). But now, in HD, it's painfully obvious that it's a different model.
The odd thing is, 2 feet is still a pretty decent size for a model (larger than the old ERTL model kit, in fact). It's kind of strange they couldn't get more detail or better lighting into it.