One thing we know about Bruce Arians is that he loves to work deep in the passing game.
His favorite characteristic of a wide receiver is speed and he will invest in one every single year.
2013 - Ryan Swope (4.34 40)
2014 - John Brown (4.34 40)
2015 - J.J. Nelson (4.28 40)
2017 - Chad Williams (4.37 - 4.4 40 depending on site used)
Anyway you slice it, Arians likes speed.
It opens up the offense and allows you to do different things.
The other reason, it makes defenses keep a player deep, if they don't, it opens up the deep pass.
We saw that in 2016 with J.J. Nelson:
Nelson's deep targets were part of the growth of the Arizona offense. Except, his growth was really the only one that occurred in the Arizona wide receiver corps.
If Nelson can continue or even grow on what he did in 2016, and Arizona gets one other wide receiver not named Larry Fitzgerald that can take advantage, watch out in 2017.