To put this in greater perspective, I'd no doubt be faster out of the blocks than I would 13 yards down the track.
From there it would be huff and puff and TRY to cross the finish line. Maybe with a rest break at the 27 yard mark...
Seriously.
Some of the best all-time players in football have so-so forty times but once they're moving, they're plenty fast. Kupp and Puka are both like that. I recently posted a link to an excellent article giving the 40 times of some of the game's best receivers. You'd be surprised how may were over around 4.6.
As far as football speed goes, I don't know what Deacon Jones' official 40 track time was, but he did run a 4.7 forty - from a standing start. On turf. Wearing pads and cleats.
In team drills he beat everybody - including Jon Arnett - in wind sprints. And "Jaguar Jon" was fast.