All of this is considered splitting hairs, from an evaluation standpoint. Combine numbers are just part of the various measurables coaches and professional evaluators use. Far be the determining factor. No player has ever run his combine speed in game day gear, so it’s all relative. What is measurable on the field of play is as Madinsomniac stated, speed burst and change of direction skill. Chris Johnson was extremely fast on the field in pads. However, Willie Parker was faster. I‘ve seen both play in person on the field, and WP definitely was faster in the open field. But neither were Combine speed fast in pads. Of the DBs….(young) Deion Sanders was the fastest and Ike Taylor could keep up with Mike Wallace during camp races.
One note, a friendly reminder that when showing a source to prove a point, Wikipedia, is not the source to use.