Greene and Thomas were among 15 players worked out by the 49ers at the team’s rookie mini-camp this weekend.
Thomas was signed by the New Orleans Saints as an undrafted free agent last year. He subsequently spent time with the Raiders and on the Falcons practice squad, where he remained throughout the 2013 season. Thomas then signed a Reserve/Future contract with the Packers, but was released on May, 12.
Thomas is a Stanford graduate, joining LB Shayne Skov as former members of the Cardinal now trying to stick in San Francisco. Thomas likely faces an uphill battle to make the team.
Greene was signed as a undrafted free agent this year out of USC. He appeared in 37 games for the Trojans, playing linebacker in addition to the tight end position.
Marquardt spent last season on the non-football injury list. He has not appeared in an organized game since November, 2011 due to various injuries. He was signed as an undrafted free agent last year.
Breslin was signed as an undrafted free agent out of USC this year. He too battled injuries throughout his college career, and as a result, he appeared in only five games in his final collegiate season.