Another reason they're slower with the heroes now is that they're taking time to do them "properly" in one go. They could probably squeeze them out at a decent rate (maybe not tri-hero updates like those leading up to TI2, but 1 every 2 or 3 weeks) if there wasn't a focus on doing so. This includes things like broken-down model, better textures, more bug testing for heroes prone to issues, etc. It most likely saves more time and headaches in the long run than getting a barebones version out then having to fix it later. Besides parity (or *gasp* even new heroes!) they've got about two dozen heroes in need of touch ups or more extensive reworks to put them at the level of quality as their latest stuff. And at least 6 or so that are in desperate need of makeovers (some of which, like SF, that we know about already).