If the three QBs are off the board I'd prefer the Rams go with an offensive skill player. It would be a small reach, but the need is enormous and it's better than reaching for Cook IMO. Some options there in order:
1. TE Henry. He's gonna be off the board in the early 20s, so 15 is not that bad a reach. He would be far more impacting to this team's win/loss record than a CB for the depth chart. Just line him up in Cook's role in the offense and watch him reap first downs for this offense.
2. WR Doctson. I've been wrangling over him vs Treadwell for some time now, and tbh I think Doctson helps the Rams more than Laquon does because of his great hands, catch radius and leaping ability. The dude can make up for QB inaccuracy, basically, which edges him above Treadwell and his size.
3. WR Treadwell. Like the two above him I see Treadwell as a guy who would fit nicely what the Rams do. Physical receiver who is perfect for our division, makes contested catches and muscles DBs for extra yards. Probably the best run blocker among all the wideouts, which is something that is often overlooked.
4. WR Shepard. This guy is not a typical slot receiver. He will be able to line up out wide and get mismatches. Basically he fattens this group and allows for the Rams to move down if the QBs go off the board quickly and still know that they can get a good WR. Uncoverable. Feisty, and best instant-separation option in this draft, which is going to benefit whoever drafts him greatly on third and short type downs.