Cooks seems like a great guy. Puff piece or not he is just a good dude and really smart the type McVay likes.
OBJ is probably a better receiver, maybe the best in the league but he is a bit of a head case and has had availability issues. He also cost twice as much or more and would be a more expensive and harder long term sign.
Most of all we had a willing partner who was ready to do a deal now.
When you weigh factors the Cook trade was the way to go. We needed to fill the X WR need badly Cooks fit the bill and the price was high but acceptable.
OBJ had much more risk in terms of contract and attitude and at a much higher price. The added risk and uncertainty was not worth it.