Well I guess I've had the benefit of watching Swope over the years, but gauge the speeds he runs by the DB's speeds and he's always as fast or faster. Then match him up with solid competition and you'll gain an appreciation for his speed. That's the best I can say, because there aren't a lot of full games on youtube or freely downloadable.
I actually agree with you that Tavon Austin's playing speed is faster than Swope's. But, he's the fastest top player at a major college level in this draft. There are a couple of kids from Texas and a few others spread around that are also blazing fast, but none of the major players on a team in a major conference really. Austin proved faster than every defensive player he faced all year. He was also insanely quick with tremendous burst and change of direction. I'm not saying Swope has all that. What I am saying is that Swope is also faster than almost every defensive player he faced, and he also has tremendous explosion.
The 40 yard dash measures multiple things together:
1. Starting burst
2. Acceleration
3. Top Speed
4. Technique
Bad technique can really hurt your score, but very few prospects have truly bad technique. The kid Marquise Goodwin from Texas is on the track team, so he had great technique, but even that showed he was running very closely with Tavon Austin the entire way, and the technique is probably what put him over the top. On the field Tavon Austin looked--to me--slightly quicker and possibly faster. Even assuming Swope doesn't have that phenomenal starting burst and change of direction that Tavon Austin does, you have to admit that he either made up time with his acceleration or his top speed. Acceleration is separation on medium routes. Top speed is what scares safeties back and separates on deep routes. But, the 40 time is just one measure of explosion.
The most used other measures of explosion are the vertical jump, where Swope jumped a phenomenal 37 inches. Your suggestion of Justin Hunter was great, as he posted the highest vertical at the combine of 39.5 inches. At his pro day he jumped 40.5 inches ... and he was an international caliber high jumper. But any way you look at it, 37 inches is tremendously explosive. Another measure is the broad jump, where he also excelled. Quickness and change of direction are harder to measure IMHO, but the tests for them tend to be the 3 cone drill and the short shuttle, both of which Swope did very well in also.
I listed some things that Justin Hunter didn't have, but let's be clear, I've been a huge Justin Hunter fan for a long time, and prior to the season was hoping we'd get him in the draft with our first pick. But he's an AJ Green type receiver, an outside receiver. Even with his flaws, his size, length, insane leaping ability and 4.44 speed means he'll go in the first round. He'll just take a little while to develop. But, he could become an AJ Green type of player on the outside. With Wallace and Hartline, we will not select Hunter or Patterson in the 1st.
I agree with you though, for judging bust ultimately you need to look at the tape, as quickness in under-armor isn't the same as quickness in football pads. And I also agree that Swope's run style looks funky, as he does swing his arm kinda wildly. But, don't let that detract from watching him run, because he's gliding past people rather effortlessly from the waist down. It's only the upper body that looks funky. And, he pulls away from DB's consistently.
Hunter is a 1st round WR in my eyes and I'll be surprised if he falls out of the 1st even with this great depth in the WR class. Swope is a 2nd rounder. Why? Because Swope is 6'0 and Hunter is 6'4 with longer arms and 3 inch higher vertical. It doesn't matter how much higher than a DB Calvin Johnson goes ... if he gets above the DB and catches a TD pass, it's 6 points. If Calvin Johnson were 6'0 instead of 6'4, Calvin Johnson would be Andre Johnson's little brother.