How are you the better prospect without being the better player anyway?
Now to look back at that example. If Vince gets injured it doesn't matter because they already know he will be a project and he brings good athleticism to the table. So he doesn't need to work out to see if he can play at pro speed right a way. Now as for Matt those work outs mean much more. Team wanted him to be a ready starter because he was more of a finished product. It he can't show that right off the bat his stock drops a lot more. Teams will be more likely to pass on him for other QBs with higher upsides.
To go back to the comparison at hand. Mays had a very high potential based on what he could do physically. There was never any question he had pro speed. Technically he wasn't a very good player but because of his natural ability, he really didn't need that in college. Teams weren't looking at him to step right in he was a project with a very high up side. Now all he has to do is come to his interviews wanting to learn and he would have been a 1st round pick, injury or no. He didn't. He came to the combine all cocky then blew his interviews and dropped like a dumb rock.
Barron is not a physical dynamo and doesn't has a very high up side. You can't say he will have an edge over other pros unless you actually see it in workouts. He may struggle at pro speed right off the bat and be useless. His stock is based on the fact that he can step in and contribute for a team that needs a S. It is hard for teams to say he has pro ability when he hasn't worked out vs already pro talent. So yes teams that are looking for a starter will be less likely to take a gamble on an injured rookie.
Yes you may say any draft pick is a gamble. That is why these teams look at everything. If they are missing a big piece of that puzzle yeah players tend to drop. That is why so many high up side players skip the combine and focus of the work outs. Teams already know if they look better then the rest of the rooks. Guys like Mays and Young don't need to show off their speed and strength. Teams already know they have it.
He fell because of what he could do physically, which is run in a straight line and hit hard.To go back to the comparison at hand. Mays had a very high potential based on what he could do physically.
Young went that high because he was a QB...An exceptionally athletic QB who had just carried his team to the NC....As in his potential was very much indicated by his on field play in college...the more people saw Mays play the more he got exposed...HUGE difference even ignoring that more exceptions will be made for QBs with potential than any other position...the only one that even come close to QB in that area is pass rusher, where teams will fall for size/speed pretty easily.
Again, Barron is a siiiiiiiiiignificantly better prospect than Mays once you get past Mays' 15 minutes of hype (which quite a few guys get during the draft process).