Kerley accumulated 152 yards on 16 receptions last season, his fifth year with the New York Jets. The slot receiver was battling for a roster spot deep in Detroit's pecking order.
Kerley, 27, earned his best season in 2012, when he compiled 56 receptions for 827 yards. His playing time waned over the past two years. Kerley could be a nice complement in Chip Kelly's spread system. Behind Torrey Smith and Bruce Ellington, the competition is wide open for snaps in San Francisco.
The trade likely explains why Kerley didn't get any run in Saturday night's preseason tilt.
Thomas was a former third-round pick who tore his ACL in a pre-draft workout. Thomas is listed as a guard, but played tackle in college. The 25-year-old offensive lineman never participated in a regular season game with the 49ers.
This was likely a case in which both teams were swapping players who would have been cut candidates next week.