Also don't forget to view the short interest in parallel and the price performance once it topped out, and the fact that the short interest before December 2014 was miniscule. They were shorting directly into the rally they were creating based on their reputation alone. That reputation bit is what makes it very likely that the price will run again in order to continue cementing that reputation and enabling the cycle to recur.
Pearson hit piece? Nothing but a cover to make the mounting short position seem "organic".
I calculated the cost basis of the short position as of last summer to have a floor of about $150M, using month to month VWAP since December 2014. I use "floor" because it's a virtual certainty that they ran the price up and down all the time and that contributes profits in the interim period between establishment of the position and now.