Elk numbers are way down, and that's not from just a few studies. The Wyoming Game and Fish Department are not out to destroy the wolf. And yes, the shrinkage of the herd began after the introduction of the Canadian grey wolf. The WG&F, as well as most others, initially blamed it on the wolf.
Soon other studies started indicating it was due to other factors as well. That may well be, and I'm not arguing what's causing the reduction of the elk population, but it is way down. This
news article, originally from the Billings Gazette, states that the northern Yellowstone elk herd is less than a quarter of what it was before wolf introduction. Blaming it on the wolf isn't pc these days. Besides, that wasn't the question posed by the OP. Yes, it down considerably. I'm thinking it's been cut by 50% or more in western Wyoming.
But hey, the Canadian wolf count is way up.;)