This isn't 1965, with teams playing man to man and a Bob Hayes can just blow by cornerbacks on pure speed. Of course you'd like to have the 4.35 speed receiver for the occasional out and out fly or post route, and if your speed guy gets past the defense he has a better chance of taking it to the house.
But just check out the stats from the last SB - longest pass play was 33 yards, and that was by Kelce, who ran a 4.61 at the combine. Longest pass play by KC was to Evans, himself a 4.6 forty guy.
Not to say a speedster can be valuable, but it's not necessary for SB wins.
