I think Shawn Nelson has a unique skill set that can be taken advantage of and is in the mold of what CHan might be looking for in a TE. He is the pass catching/athletic type that isn't known for his physicality, and with Chan's spread style offense, can create some mismatches with opposing defense's smaller personnel.
I read somewhere that the undrafted FA TE from UNC the Bills picked up will be the #2 TE this year. He has had a history of injuries in his UNC career, but considering all the games that he missed, he still is the UNC record holder for most catches in a career.