Nathan Overbay is an undrafted rookie free agent from Eastern Washington University, basically a complete unknown. A draft scouting report from CBS Sports characterizes him as a very raw prospect, whose best trait is his hands. However, he's said to lack speed and be a medicore blocker, though he certainly has the size to improve there. This is odd to say the least. With Kellen Winslow, John Gilmore and Ryan Purvis the team already has 3 tight ends on the roster and there's not a lot of depth along the offensive right now. My best guess: this is a tactical decision and we'll be seeing a lot of run-heavy and TE-heavy formations against the Seahawks on Sunday.