Smith, when healthy, is a very versatile player. He can play Wide Receiver, Wildcat-formation Quarterback, as well as return kicks but not so many punts. If he passes the physical, Chip Kelly has just found himself a new offensive and special teams weapon to add to his arsenal.
Over the past couple of weeks, the Eagles have enjoyed the recent hot streak of Riley Cooper, but adding Smith could add another set of hands to take some of the attention off of Cooper and DeSean Jackson, who will certainly be garnering all attention in the last half of the season. Smith could be listed as high as 4 on the depth chart behind Jason Avant due to being used only in certain Bills and Jets offensive situations in the past.
Another way Smith can improve the Eagles is on special teams. Damaris Johnson and now Brandon Boykin have been struggling in the return department this season and Smith is a historically good return man. Look for him to be mainly used here in the beginning weeks before he can learn the Eagles offense.
Below is a video from the 2010 season of Smith returning a kick for a touchdown and losing his shoe in the process. Hopefully he can break one of these before season's end.