There is nothing in this at all, Purito made an attack, Contador followed, was catching his breath as he said and didn't feel like immediately jumping on the next wheel, Froome's in that case. So he was looking at Valverde to do the pace only it wasn't fast enough to keep Froome in check. When he realized that he accelerated himself for a couple of seconds, didn't manage to drop either Purito and Valverde and after that made no further efforts to get away from the group, despite having had a great opportunity to jump up to Froome/Aru after the big turn Purito made, most likely because he had to catch his breath again. After that he did a turn of steady pacemaking under the last km banner and at the line was outsprinted by Valverde and Purito.
To me that looks like on this particular day on this particular climb, Aru was the strongest, Froome second strongest, and Contador third along with Valverde and Purito.