I don't recall what sort of numbers Charles Woodson put up when he won it, but I think in this day and age a defensive player is going to have to put up ridiculous numbers. Ndamukong Suh was one of the most dominant defensive players we've seen in a long time, and he couldn't get more than 4th place.
But unless Peterson has like 8+ TDs and 10-15 INTs, I don't think he has a shot to get on the ballot. Not to mention, he has to have some really dominant performances against Florida, Alabama, and Arkansas, which is possible...but still a ways off.
"Vincere scis, Hannibal, victoria uti nescis" -- Maharbal, 216 B.C.E.