Physical talent makes a difference. Just enough to get you into the NFL.
To be great you have to have mental ability to work your craft like a scientist. Not everyone is a true scientist at their positions, and the talent required to be good.
Route running is not only about the physical skills, speed, flexibility, agility ad explosiveness, but is also about subtle things that fans typically don't know until you have to run the drills a 1000 times yourself.
The biggest difference in route running that an NFL player has over even the most physically talented fan is the balance. They lay within what I call their circle of balance. The best sport for this is soccer where the majority of the play is based on one on one match ups. Soccer players are trained to work you and your balance where you "wrong foot" yourself, and take yourself out of the play.
That is the talent you see displayed in the short video. If you want to be a master at wrong footing an opponent, then you have to be a scientist at the craft.
There was no way Dez Bryant was ever going to be that. He is no scientist, and his ability was limited to what he could accomplish physically. He never brought his mind to the game so when his body failed him in competing physically he had nothing of value to bring to the NFL field.
For any NFL player father time will always beat you physically. What a player needs to invest in right away from day one is the work ethic to expand your ability beyond the physical. Not everyone is born a Bo jackson of their draft group. Most have to work their ***** off, and bring a higher mental capacity to make the ProBowls and the HoF.