The year Martay almost made the probowl as a special teamer, he was a good kick returner. Why? That year, he was trying to make a name for himself and played KR like a mad man.
The next year, when he became the #3 WR, his attuditue was like "why should I risk myself as a KR when I'm now a starting WR". He was tentitive and eventually got benched as the KR.
I don't think he will ever get that fearless attutidue back as a KR, so I wouldn't really want him playing as the KR again.
But, he is a very good gunner on special teams so I'd take him back again as a gunner.
Now, how will his ego handle it? Don't know. I may consider waiting until week 1 is over before signing him (if someone else wants him, so be it). That way, he will have the fear of being cut on him all year. If the Cards sign him now, he gets paid for the entire year no matter what.