By Olin Buchanan

All-Big 12 defensive backs Aaron Colvin and Tony Jefferson of Oklahoma could pose major problems in the Cotton Bowl for Texas A&M’s Heisman Trophy-winning quarterback Johnny Manziel.

However, two other guys could prove greater obstacles for Manziel — Jay Leno and David Letterman.

History shows Heisman Trophy winners frequently struggle in bowl games. In fact, Heisman recipients are 25-27 all-time in their ensuing bowl games.