Dude, I don't think they're looking at it that way. I think the bringing in Tavon Austin and not bringing in Ertz or Eifert pretty much says that they don't view Cook as just as a slot WR in the offense.
Plus, both Ertz and Eifert are move TEs who have a long ways to go as blockers before they can line-up inline in the NFL(I don't know if Eifert ebut it would be cool, and it would be a viable option that could have some success if they let me be the OCver will effectively). In that case, you're essentially drafting the same role as Jared Cook.