DiMarco (6-1, 243) played in five games (four starts) with the Chiefs in 2012. He originally joined the club as a free agent in August of 2012 after a short stint with the San Diego Chargers in 2011. He was signed to the Chiefs practice squad on Sept. 1. The Altamonte Springs, Fla., native was a team captain at the University of South Carolina where he played tight end and fullback. He prepped at Lake Brantley High School in Altamonte Springs, Fla.
Greenwood (6-2, 235) saw action in 48 contests in three NFL seasons with the Chiefs (2010-12). He served primarily on special teams, recording 34 tackles and one fumble recovery. On defense, Greenwood tallied eight tackles (seven solo). He originally entered the NFL as an undrafted free agent with Kansas City in 2010. The Kingston, Ontario, native played collegiately at Concordia University in Montreal and prepped at Regiopolis-Notre Dame Catholic High School in Kingston, Ontario.
Mattison (6-3, 310) played in 19 games (four starts) in three NFL seasons with Kansas City (2012), St. Louis (2011) and Baltimore (2010). He spent two seasons (2008-09) on the Ravens practice squad before moving to the 53-man roster. He originally entered the NFL as an undrafted free agent with the Jets in 2008. He was a two-year captain at the University of Iowa, where he played on the defensive line. He prepped at Penn High School in Mishawaka, Ind.
Tanney (6-4, 220) originally entered the NFL as an undrafted free agent with the Chiefs in 2012. He played collegiately at Monmouth College in Monmouth, Ill. In just over four seasons with the Fighting Scots, Tanney played in 47 games, completing 1,205 passes on 1,756 attempts (68.6 pct.) with 157 touchdowns and 30 interceptions. The Normal, Ill., native played quarterback at Lexington High School in Lexington, Ill.
— Chiefs Media Relations —