There are two issues: one is the tech panel, who gave Piper and Paul Level 3 on both step sequences and the spin. That is 4 points right there. 6 of the 7 teams ahead of them got all level 4s. Some of those teams, particularly Cappellini & Lanotte had more than one error that could have been easily have been called, and Hubbell and Donohue and Papadakis and Cizeron had at least one element that had an error. They were extra picky with Piper and Paul and lax with the others. Correctly called, I would have had them certainly ahead of Hubbell & Donohue and Cappellini & Lanotte in the FD.
Cappellini & Lanotte were twelfth to skate, and I did not think well of their performance in any respect, other than their costumes looked good. And then they got higher marks than Virtue and Moir's Carmen in 2013, and just a hair less than Davis and White's Notre Dame de Paris. And I am thinking, whaat the heck are the judges and tech panel doing???.? Those were both amazing performances. This was a rerun of C&L's previous Nino Rota film score FDs, and not performed that well.
Worlds FD 2013
http://www.isuresults.com/results/wc2013/SEG008.HTM
Worlds FD 2016
http://www.isuresults.com/results/season1516/wc2016/SEG008.HTM
Piper and Paul did not get those type of favors, but they still got personal bests in all categories. Weaver & Poje had a noticeably flawed skate. Andrew looked so sad and deflated in the KnC (I saw him on the Jumbotron), and yet Kaitlyn & Andrew received their best ever FD score.
It was crazy.
As to Piper and Paul's dance, as I said, it did not impress me as much as their SD, but I surely would not have had it as low as eighth.
Some things I noticed:
I found the music droning and kind of repetitive.
They used a number of little hops and jumps in their choreo. The appearance from our seats was that they lost alignment with each other, rather than that they had hopped. If you hop, you have extra difficulty to keep alignment because of the discontinuity of the hop. This is especially noticeable when you sit higher up as we did (mezzanine level).
Some of the extra touches that look cool in the video just looked a little odd or untidy from higher up. This is particularly true of their stationary lift. Paul is down so low to the ice that it was not clear it was a lift and not a spin or choreo spinning movement.
I found the stuff Piper had drawn on her tights just distracting. I kept trying to figure out what the signs/words/whatever were meant to be.
Finally, rather than seeming completely new, it reminded me a bit of an FD Paul did with Vanessa Crone where one was in red, the other in blue, and it seemed to be about making cool abstract shapes, including having references to a British flag, AFAIR, I believe Christopher Dean was involved with the choreo for that piece?