Bradford, 24, is a former fourth-round pick of the Packers back in 2014. He managed to make the 53-man roster during his first year in the NFL before being converted to inside linebacker this last year.
Bradford spent the 2015 season on the Packers their practice squad and was unable to make the 53-man roster coming out of the preseason again this year. The Packers later signed him to their practice squad before calling him up a month ago.
Green Bay waived Bradford back in December and he was later claimed off of waivers by the 49ers.
In 2016, Bradford appeared in six games and recorded five tackle and no sacks for the Packers and 49ers.
Purcell, 25, wound up signing on with the 49ers as an undrafted free agent out of Wyoming back in 2013. He was unable to make the 53-man roster during his rookie season but was later signed to their practice squad.
Purcell returned to San Francisco on a future/reserve contract and eventually worked his way onto the active roster towards the end of the 2014 season.
In 2016, Purcell appeared in 15 games for the 49ers and recorded 26 tackles, no sacks and a forced fumble.