Mark Kelso was a dynamic safety for the great Buffalo Bills teams of the early 90s. After his playing career Kelso served as a color commentator for Buffalo Bills Radio Network and also as an elementary school teacher and football coach.
Kelso was one of the players I remember that wore the cap over their helmet to minimize concussion risk. The cap is visible here in this card. From what I remember the caps were made of a Styrofoam material and I have memories of the helmets at the end of games with paint and foam missing.