Miami Dolphins make the biggest loser move in FA............by far! (title edit)

Then why did they sign the best deep threat WR to QB $$$ for a #1 draft bust QB, that can't throw the ball further than a lingering fart? Tua's Yards per throw is in the dumpster. Is it the WR that makes the QB? How do they move off Tua if he underwhelms again, after paying Hill?