Speca didn't see an increased role at the position in 2025 despite Tony Rojas' season-ending injury.
Wafle transferred to Penn State from Michigan a year ago.
Boyer notched his first career start in the Pinstripe Bowl.
Williams is Penn State's first non-Iowa State transfer addition.
Birchmeier played in 26 games over the last two seasons.
Robinson is the fourth former Iowa State wideout to join Matt Campbell in Happy Valley.