I haven't watched, read, or studied how or what method of timing is used in the combine, but you and irish4ever both bring up good points. That is also why I asked for the source of info on the recruiting profiles forum. Did dad submit the time, or did his football coach submit the time (handheld, on the grass), or did his track coach submit the time on the track... I understand that Rivals and Scout etc... do their thing, but I was curious as to the timing "system" used for times reported. I assume they are hand-held and flawed, give or take by .2 - .3 seconds, as evidenced by Tate's initially reported time vs. the official...
Hand held watches that start after the athletes push off are delayed timing starts, and make the athlete look faster. FAT timing makes the athlete look slower. I suppose if you really want to get more precise about speed, maybe the best answer would be to have FAT timing that begins the moment the athlete pushes off of blocks at a certain force.
But since this is not a track meet, as long as timing is consistent and coaches are impressed with the athlete, that's all that matters. A 4.36 and a 4.42 aren't much of a difference when running routes. On the track, that difference is about an inch or so.