Haven't used them in a while, but I haven't noticed any patch notes or other indications that there would be an intentional change..
Are you comparing like to like, as in is your spec the same? The brawler spec gives most of the stuns, without the points they're going to be a lot less stunning.
A higher difficulty might also have an effect.
The book series, maybe, I don't think it has straight up usable stuns in it, but even a damage increase may have an impact.