Case Keenum
Keenum has been one of the NFL’s more interesting veteran passers over the last few years. He erupted in Minnesota in 2017 in great circumstances, which landed him in Denver as a starter. He flopped there and got traded to Washington, where he also (mostly) flopped.
A journeyman at the age of 31 with a career 62.4 completion percentage and 75 touchdowns against 47 interceptions, Keenum probably isn’t going to get another stab at starting.
But the Bengals would probably welcome Keenum as a game-managing backup behind a rookie who can impart plenty of knowledge after his five-team NFL journey so far.