Vince is faster than you think in the 40 and its largely because a lot of people lie about their 40 times. VT is the most notable example of this. Ever VT player loses at least 2 tenths at the combine. Also, a LOT of nfl people questioned the USC pro day stats. Matt leinart vert jumped 38. That is the same thing as Devin Harris. Justice verted 37.
As for vince, he ran a 4.48 after just taking off his sweats and running once. That means if he ran it again he would probably run somewhere around a 4.4 flat and he has always said he runs a 4.42 so that makes sense. The thing about the game speed is that pads dont hurt him running which is why he has great game speed while some track guys cant run with pads.