Zinoviev Letter said:I don't think it was intended as a defensive move (although if he turned out not to have great legs it would have functioned as one as a fallback). it was an attempt to gain back much of the time he lost yesterday. He presumably had the legs to climb with the leading five if he hadn't attacked, given that they barely took 40 seconds on him on the climb after his distance attack.
He was worried about losing contact with repeated attacks. His main aim was to ride at his own pace and if possible pick up some time. Top 5 still a possibility could have been even better if he hadn't blown so much yesterday.