Felix does have terrific vision, balance and instincts. Still, the thrust of the original post is that:
A) Felix ran a 4.47 forty at the combine.
B) Demps ran a 4.39 forty at the combine.
C) Felix was a couple of yards ahead of Demps at about the 50 yard line.
D) Neither player was inhibited by anything from there to the endzone (although Felix did have to carry a football).
E) With both players running full out, Felix was pulling away from Demps.
F) Felix is faster than Demps when playing football.
Conclusion: The forty times at the combine aren't always correct, although they are indicative of a players speed or lack of speed.
IMO, the training that players get on coming out of the blocks and running a forty yard dash has skewed the results a little bit... not to mention that players carry their pads differently (i.e. pads slow down some more than others).
That's why I was saying that I don't care what Mendenhall ran at the combine... Felix is a good deal faster playing football than him.
When McFadden and Felix entered the draft, everyone said Felix was the faster of the two... after the combine, nobody said that. However, once football began, we see DMC get caught by a safety and Felix outrunning everyone.
This is a very good lesson to remember. Take the combine and pro day forty's with a big grain of salt. Not only is there a lot more to football than speed... but that speed (track) isn't always translated to on the football field speed.
