Doesn't it seem likely that he didn't do anything differently with them, and that they were able to step up as a team because of who they are as competitors & athletes? (They seem very even-keeled). They also would benefit from having a strong choreographer work with them, IMO. They have plenty of natural expression. At this point it's just straightforward smiling, rather than interpreting the music; but it seems like they should be able to make the leap.