In week 3, according to Next Gen stats, Josh Allen's 10 yard run for a TD against Minnesota was clocked at 20.6 mph.  While not an exact science, you can roughly convert mph into a 40 yard time by dividing 80 by the MPH, so this comes out to an astounding 3.88 40 yard dash time.  Obviously this is from a running start, but even so, his 20.6 MPH put him in between Saquon Barkley and Christian McCaffery for fastest runner in week 3.  Again, this week, Allen was clocked at 20 MPH on his 45 yard run