I agree with you and your concerns about him in a nickel. Many teams also will line up their pass catching tight ends in the slot these days. Matthieu covering someone like Gronk or Graham would not be good for him.
I also agree that there is a place for him on an NFL team. I was so mad at him last year for all his screwing around. This guy is definitely a playmaker and can help a team in ways that many people can't. I certainly believe there is a niche for him if he can just stay out of trouble.
I like this potential draft but I really think someone would have to blow our socks off for us to trade down. The more I think about it the more I believe we will be staying at 15 and taking Jones, Ogletree, Mingo, or Austin. I see this as a weird draft where a top 10 player is still on the board at 15. *Fingers crossed*