How can Elsevier claim that its OA revenue stream is separate from subscriptions in a hybrid environment?

For an open-access advocate, it's easy to pick on Elsevier. An enormous and immensely profitable publisher, it has been, in my personal view, obstructive towards the implementation of open access. Again, in my opinion, this seems to be because it fears for its revenue stream, rather than because it cares about science. The ElsevierValentines hashtag was puerile, but fun, and demonstrated this sentiment. But these are just my opinions.