The article implies there's been a decrease in the median wage, but there's been an 8% increase YoY according the SSA. In real terms there's probably a net decrease in the median wage but nonetheless.

Most New American immigrants that come here do not have the intellectual capacity to contribute in the modern post-industrial society. This makes a sharp contrast with the immigrants of the 18th century that came here without counting on welfare benefits welcoming them. Since these new groups of people comprise 30 to 40% of the American society , we see the reduction of the middle class.