My completely uniformed opinion on what the root cause of last year's dropsies:
I can't remember ever seeing a team that subbed WRs in an out of a huddle as often as we did last year... and we weren't a team that tended to huddle. Prior to 2016 - You could pretty much count on Doctson and Listenbee being on the field the majority of snaps. Last year we had a BUNCH of GUYS getting A BUNCH more snaps lining up in MULTIPLE WR configurations.
Doing things like this takes a LOT of practice...and I doubt the majority of our wideouts ever felt like they had a comfort level they were at least 95% locked in. Trickle down effect = Reduced confidence and comfort level. Complexity (necessary??) forcing emphasis on everything leading up to having to make a catch....makes it harder to just go out and catch.