You have to mean 4.9 seconds. If he runs 3.9 and can prove it, every d1 school in the country will want him.
Here is an article about the runner up Heisman trophy winner Mantei Teo
"Manti Teo improves time on 40-yard dash at pro day By Xai Xiong March 27, 2013 After running 4.82 seconds in the 40-yard dash at the NFL combine, Manti TeO improved his time with 4.75 and 4.71 seconds at Notre Dames pro day. I felt good. Im at home now, Teo said. I was very pleased with how I performed. With the time that TeO received in the NFL combine, many teams were suddenly afraid to draft him in the first round of the NFL draft. "
He used to tell the other players in high school that they would go faster if they really pumped their arms.
The fact that he got a spot on a D2 school was a great accomplishment for him.
He was really fun to watch though when he ran and played defense on the basketball court.