Miller is the No. 8 overall prospect coming out of Virginia, according to 247Sports.
"One of the first things I told Coach Pry when he left was that the standard's not changing. I'm still gonna expect greatness from the young guys -- still gonna teach them, coach them."
Smith totaled 131 tackles over the course of his three-year career for the Nittany Lions.
"We had to do better in the city limits. We made a conscious effort to own our mistakes."
Diaz has led successful defenses at Texas, Middle Tennessee, and Miami.
"I could not pass up the chance to be with this family and play the game I love again."