In 607 innings career-wise (I believe only minors) Sampson has allowed 302 walks.
In the minors this year he had 82.2 innings and 46 walks.
In the majors 2015 before tonight he had 31 innings and 16 walks.
Tonight is one five inning stint so far. But this is a significant problem. And usually when a pitcher is that walk prone it indicates a greater command issue.