Kurt Busch's crew chief, Steve Addington, has left Penske Racing following the end of the 2011 season.

Addington was rumored to be leaving the organization as recently as October, when the series raced at Charlotte Motor Speedway. Penske Racing president Tim Cindric confirmed the official decision Tuesday morning.

“Steve Addington is no longer with our organization,” Cindric said. “We appreciate the successes we experienced together and wish him the best in his future endeavors.”

Busch and Addington worked together for two full seasons and won twice in 2011, but finished outside the top 10 in the final standings despite making the Chase for the Sprint Cup. Busch lost a transmission at Homestead-Miami Speedway and lost his cool in the immediate aftermath.

Addington's next move could be to Stewart Haas Racing, where Darian Grubb will not return as crew chief for new 2011 champion Tony Stewart. Addington worked with Kyle Busch before accepting the deal to join Penske Racing.