It does help to have a deep threat though. During much of James Jones' career, he was halped by the fact that the Packers had Greg Jennings and Jordy Nelson, guys who had deep speed that defenses had to respect. The Packers need to get back to drafting one of those types of guys. It would Adams even better.
It also helped to have James Jones, who despite pedestrian speed somehow got an angle on DBs. Once he learned to catch over the shoulder he was a nightmare to cover deep.
Mostly I think his advantage was size and the willingness to run some inside routes. DBs had to honor his feints inside.
Bud Adams told me the franchise he admired the most was the Kansas City Chiefs. Then he asked for more hookers and blow.
Most definitely: the tiny DB goes backwards. As you alluded to in your earlier comment, a good deep threat doesn't necessarily need blazing speed. Knowing how to use positioning and hands, and being able to do something after catching the ball, are just as important. What made Jones especially tough is that he was hard to bring down and had some quickness, so those 30 yard back shoulder throws had a way of turning into 65-yd TDs.