There's a good discussion on "The Football Show" podcast either this week or last week about slots.
The reality is that we just don't see as many Edleman types in that spot anymore.. maybe it's cyclical. You'll note on the Jags biggest gain on Sunday they had a big WR, Laquan Treadwell, lined up in the slot and he just ran right by DD, who tried to flop for a penalty. If you try to hide him there against the Cards, Green is going to get moved into the slot. Offenses are just too sophisticated to hide that stuff.
Kupp plays the slot a bunch.. he's 6-2... there are more and more.
I'm pretty concerned about it, obviously.