This is not a move that should change your plans for your upcoming fantasy draft, but it does speak to the priorities of a new coaching staff.
McCown was just released by the Saints, but spent the previous three seasons in Jacksonville, where he worked with new Falcons offensive coordinator Dirk Koetter.
Redman was a vaguely functional backup, which is to say he didn’t do much the last five seasons in Atlanta. He started six games in that span, throwing more touchdowns than interceptions (21-14), but winning just one of those starts.
These kind of moves happen all the time, with coordinators preferring someone they know to someone they don’t (like Rob Chudzinski fetching Derek Anderson to the Panthers). But in most of those cases, the team in question would be in a huge mess if those guys actually had to play.
This is one of those cases. Then again, that would have been true even if they stuck with Redman.