A rookie out of Northwestern, Fields caught 114 passes for 1,203 yards and seven touchdowns over four seasons with the Wildcats. Irvin, meanwhile, is a former third-round pick of the Carolina Panthers who has played in 18 games over three seasons with three teams (Carolina, Tampa Bay and Jacksonville), contributing 11 tackles.
Tupou finished his college eligibility at USC, but went undrafted and unsigned in 2012. Tupou played in 41 games from 2007-11 with the Trojans, contributing 53 tackles, including seven stops for lost yardage.
Jones played collegiately at Temple, and made 12 starts in four seasons with the Owls.