The wave of Vikings free agency defections continued Monday night with news that Cordarrelle Patterson will sign with the Oakland Raiders. San Francisco Chronicle beat writer Vic Tafur first broke the news on Twitter.

The Raiders official account confirmed the news shortly thereafter.

For the Vikings, letting Patterson walk in free agency was a move that once seemed like a sure thing, but recently, the prospect has become more complicated. The team didn’t pick up his fifth year option after a dismal 2015 in which he recorded only two receptions. But Patterson rebounded last season, notching 52 catches for 453 yards and two touchdowns. He also became a punt team weapon, accepting the role of gunner and becoming one of the best in the league at covering punts.

Patterson’s true value, of course, has always been as a kick returner. He is a two-time All-Pro at the position, and holds the highest kick return average (30.4 yards) of any active player. His departure leaves a big question mark on who will return kicks for the Vikings in 2017.

For the Raiders, they get an extremely talented, if enigmatic, offensive player that can be used in a number of ways, in addition to his kick return duties. Patterson has been criticized in the past for having a “me-first” attitude and didn’t always get along with Vikings coaches, but expressed his interest in returning to Minnesota on Snapchat in the past few days. If Oakland can find a way to keep him engaged and get the ball in his hands more regularly than the Vikings did, they will have a very dangerous weapon.

For the Vikings, this creates an immediate need at kick returner, while also likely signaling Jarius Wright’s return in 2017. It will create more opportunities on offense for second-year man Laquon Treadwell, as well.