I look at Douglas as the discount version of Tyreek Hill (which is still very, very excellent), and I'm very high on Polk as a "go-to" receiver. Sure he's not gonna be an elite WR who flashes but I expect him to be a crafty "move the chains, get open" guy which is still great. That could be a nice WR2. He made some nice plays in the preseason and was open for a handful of them in some crucial spots.
If at least 1 of Baker/Boutte can emerge as well to go along with Henry, Hooper and Bourne I think our receiving group including TEs is actually really good. I'm just not sold on Thornton and he gets hurt often. Osborn could be a solid 3rd or 4th guy along with Bourne but it's hard to tell.
The O-Line is the biggest issue obviously. If they had an actual LT and Onwenu was at RT then I'd actually feel so much better about the team. Unfortunately they don't and Sow is probably done for the year too. They really have 3 holes in the O-Line and could be really screwed if any or both of Onwenu/Andrews goes down to injury.