Mumpfield ran a 4.59 at the combine and didn’t run the 40 at his pro day. His strength is the 20 shuttle and the 3 cone where he was one of the top 10 coming out of college. I think I saw where he was the 2nd fastest in either the shuttle or 3 cone. He was actually happy with his 4.59 so I don’t buy that he ever ran in the 4.3s - certainly not 4.2.
He’s a route technician with very good hands. He’s not known as a speed guy.