Dota 2 6.79 gameplay update makes many, many changes
Undoubtedly I will be lynched for this, but I don't really know anything about Dota 2. But I'm told that the long list of changes made in the new 6.79 gameplay update are rather significant, and will result in some big changes. Rather than pretend to know what I'm talking about, I'll just link to a forum post by a Valve developer which appears to be a preliminary list of the changes you can expect.
Thanks, Marirranya, who probably knows more about Dota 2 than me.