WR is tough to evaluate given productivity depends on targets... and of course targets depend on play design and does the guy get open or not... since we can't really see the route on TV, I have no idea is Zay gets open. But, he has only been targeted 17 times this season. That's really low. And, obviously our QBs have both had accuracy issues.
It'd be far easier to judge Zay if we had a decent offensive coordinator (I'm not a Daboll fan) and a solid NFL QB. Until that happens I'm going with "need more data" on Zay.