Caussin, who played high school ball at West Springfield and collegiately at James Madison University, last played in 2011, catching five passes in six games for Buffalo. But since then he's battled injuries. He tore his ACL in the final game of 2011, leading to him being on injured reserve all of 2012. He spent 2013 on IR with a hip injury.
Jacksonville signed him as an undrafted free agent in 2010, but eventually released him before the season.
Nelson filled in for Sundberg when the latter suffered a season-ending meniscus tear in Week 6.