I said mostly and If you don't think think she is using her arm then why the big take back? How do you think the racquet catches up to her rotation? magic? Watch her in slomo. You can see her arm moving forward faster than her torso. That means she's using her arm. As opposed to rafa who's racquet lags behind until he slow his rotation and the arm rips around.
And i said she 'uses her arm'. i didnt say she 'arms it'. there's a difference.
Yonex VCore 100s - SW 351 6pts HL Tour Bite / Luxilon 4G 16 @ 51lbs