At the right price I'd say he's worth a look, but he's not worth that much money.
I think the Rams would love to dump his contract given his stats last season but more importantly, his concussion history. While he has only missed 2 games due to concussions, his last one was his fifth (known) concussion in his six-year career, and the second within a 25 day span last year. All I can picture is Sam Shields and the last non-contact concussion that ended his season and time in Green Bay.
Cooks is really talented, but a walking time bomb for possibly having to give up football sooner rather than later. If he was a Free Agent and willing to sign a deal that reflects that fact, I would say he is worth the risk. However, he isn't a FA, the Rams will want something for him and he has 4 years left on a pretty expensive contract given his medicals.
All that said, if I read his contract correctly, he will "only" cost a new team $8M this season, since the Rams are now (3/15) on the hook for his $4M roster bonus. So if his concussions don't scare you and the Rams are willing to take a later round pick, he might be worth the risk. I just can't see the Rams "giving him away" though. His dead cap would be around $21M if traded or cut.