I don't think they are intentionally tanking. They are going through a rough patch after nearly a decade's worth of strong performance - 9 straight .500 or better seasons, multiple playoff berths, and 2 Super Bowl rings.
Teams rise and fall at some point. The Giants still have strong talent on both sides of the ball. With a couple of new pieces, they can recharge and become a playoff team again very soon.
I agree that Clowney or Mathews would make ideal targets for them, though.