Dude is the opposite of slow, although based on vertical and 40 and 10 split, it might take him a pinch to get going. He supposedly ran 22.6mph during this run below. That's darn fast. I thought I had analyzed it meticulously a month ago and didn't think he got quite up there (maybe it was my CWatson goggles), but looking at it again, I was off. He def got up there at around the opponent's 40 - good high cadence (~285spm) with what looks like ~7' steps (which is exactly 22.67mph). Would love to get the official 10 and 20 splits for his Combine 40 to see how fast he was moving from 20-40. Note that McCourty has been the fastest ball carrier for the Pats in the last 6 years at 22.05mph.
He did have ACL surgery I think in HS, but looks like he's over that. Also, he got a foot injury during camp that he dealt with all season (source: Wholehogsports) and still ran this fast.