I was looking to see what the record of Heisman winners in the national championship game in that year and found that they are 6-7 in the last 13. You can go back further but the national championship name gets a little fuzzy. Also, the last two hiesman winners to lose in the national championship were troy smith and sam bradford. Both losses came at the hands of Urban and uf.

http://en.m.wikipedia.org/wiki/Heisman_curse