He is a sub 4.4 seconds guy. In fact if Jakeem had been invited to the Combine last year, he was expected to break the record (it got broken this year by John Ross). The problem was 84 year old Gil Brandt, who controls the invitations, wants the Combine for NFL caliber footballers and not pure sprinters. Now it turns out Jakeem can play and his credentials at Texas Tech were excellent, but surprisingly, he missed out on getting an invite. Being a Texas boy, it could also be that old Gil was trying to set something up for the Dallas Cowboys by trying to generate less attention re Jakeem's 40 time.
Make no mistake, Jakeem is probably the fastest player to ever wear a Dolphin jersey and when he gets in the clear - he's gone.