Think Jimmy Graham, if you will.
The most compelling Attributes of a Flex End, in the 21st Century, are, in my view, and in no particular order:
Release ~ How Adeptly he employs Burst, Core Strength, Fluidity, & Combat to Dust Off the Defender
Routing ~ How Adeptly ~ Crisply, Intelligently, and Reliably ~ he Runs the Route Tree
Separation ~ Fluidity & Ricochet ~ Explosiveness out'f'is Breaks
Catching ~ Reliability & Technique
Navigation ~ How well he Navigates the Field in Pursuit of Yards After Catch
Blocking ~ Core Strength, Drive Power, Fluidity, and Combat
Routing ~ Extraordinary. Has a remarkable Command of Routes and terrific Vision.
Separation ~ Superior. Very Savvy & Instinctive, and very Fluid, but his Ricochet lacks Explosion.
Catching ~ Inconsistent. Great Hands, but not very Physical in Traffic.
Navigation ~ Exceptional > Shows great Instincts & Timing.
Blocking ~ Awful. Flashes Drive Power, but often fails to Finish.
Frankly, I tend to think that Ertz never quite belonged at that level.
In this emerging Era of the Tight End, I think he commands extraordinary Potential, mind you. But unless he developes into more of a physical player ~ Blocking, getting Off The Blocks, breaking Tackles ~ I expect that he'll fall short of Greatness. Even so, I expect'm to develop into a dangerous Weapon in the Passing Game.
Consensus Market Value