Have Wolves Returned Yellowstone to its Natural State?

From Mountain Journal:

Yellowstone National Park looks different than it did 30 years ago. That much everyone can agree upon. How different? And who or what is responsible for that change? The answer is where scientific opinion seems to diverge.
Most everyone has heard the story of the term “trophic cascade.” Most of us have seen the video. It has 45 million views on YouTube, in addition to frequently making the rounds on Facebook.