Honestly, I don't understand this. Why can't you buy a full 476 off-set with JP.
Because, you can, anyway. You just have to buy the version that costs 30% more and has added PvP stats.
Unless you're a shield tank, but of course, you signed up for a life of gearing misery when you did that anyway.
What are the people at Blizzard thinking? You grind JP, exchange them for honor, buy raid finder gear with a gob of extra PvP stats on it. This is how you gear your alts. Or, you grind honor, et cetera.
Why does this make sense?