You did your homework!
I actually like Coutee better than Martin (FYI, those are different teams; he's owned in the league where I have Martin). But yes, I think they're both dart throws, and very far from "must-add" status.
Martin's opportunity is a little more defined (he's the clear two-down back) whereas Coutee has more talent and a better offense. But pretty much all WR2s/WR3s are dart throws. You never know when they'll crap a 3/30/0.
With no DT, Coutee was still not guaranteed to bust out, but he had WR2 upside. Now, who knows?
Meanwhile, Sutton now has far more upside, probably even more than Coutee before the trade, since Sanders <<< Hopkins.