Funchess' stats are helped by the fact that he wasn't constantly double-teamed, or even triple in the red zone like Eifert. Besides, Eifert had more than double Funchess' yards, and Niklas had essentially the same average yards per catch, but never played because Eifert. I'm sure he's good, but I doubt he can block very well if he only caught 15 passes.
As far as Gardner, I'm not sold yet. We don't know what he'll look like when he's not a surprise, and teams are preparing for him, with decent film- I'll bet a solid 25% the plays UM ran with Denard at QB looked nothing like they were supposed to, and changed completely when you put Gardner in.