T-Mac or possibly Walker. Almost everyone else is a trade down, IMO, although you say that is off the table.
If you aren't mentioning Sanders being off the table, I would fail to see why a trade down isn't possible, however.
I don't think the argument is about the book value but about the player and the overall strength of this draft seeming to be short on elite talent. Add the fact that we have a ton of roster holes and that explains why a lot of us are against it.
Most of our issue with 2nd round WR's is picking the wrong guys. I personally don't think Higgins is the wrong guy.
That said, I do believe his path to be a star receiver is unlikely.
Trading up would be a stupid move. Trading up to get Carter would be a lightspeed stupid move.
Trade down makes infinitely more sense in a draft weak on elite talent but deep in two deep/solid starter talent.
It would be a very Tepper Panthers move to get this wrong.