Buffalo will be Roberson's fourth program in his seventh year of college football.
Walfe, who has four years of eligibility remaining, transferred from Michigan.
The Capital One Bank Guy is actually a pretty good juggler.
Shanahan became the fourth transfer to commit to the Nittany Lions.
Carter became the second Nittany Lion set to enter the draft.
"We didn't win the game, so it wasn't good enough."