That isn't entirely fair to the InnoDB/MySql developers at Oracle - from what I've heard there has in general been an increase in development activity within Oracle. Some of that is merging patches from downstream, but most of the work has been on other improvements.

Performance in 5.6, for example, has improved a lot even over patched versions - e.g. https://www.facebook.com/notes/mysql-at-facebook/can-innodb-...