He worked as a Cup Series crew chief for Team Penske in 2010 and 2011, Stewart-Haas Racing in 2012 and 2013, and HScott Motorsports in 2014, 2015 and 2016.

Addington worked as Jason Keller's crew chief in the Busch Series, and the combination collected 10 wins.

18 car in the NASCAR Cup Series driven by Bobby Labonte, replacing Michael "Fatback" McSwain.

[9] Busch ended the season with 21 victories in NASCAR's big three divisions (Sprint Cup, Nationwide, and Craftsman Truck Series), which was seven more wins that any driver had made since the Craftsman Truck Series began in 1995.

"[4] After Busch missed the 2009 Chase, Addington was relieved of his crew chief duties with three races left in the 2009 season was replaced by Dave Rogers.

On December 14, 2009, it was reported that Addington would become the next crew chief for Kyle's brother Kurt Busch at Team Penske, replacing outgoing crew chief Pat Tryson, who had been relieved of his duties following the 2009 Sprint Cup Season.

14 Chevrolet, driven by SHR owner/driver Tony Stewart and Team Chevy, taking over for 2011 Sprint Cup championship-winning crew chief Darian Grubb.

Addington missed the race at Talladega in October 2013 as his wife was about to give birth to a child.

[11][12] In 2016, Allgaier went back to the Xfinity Series was replaced by Clint Bowyer and the car was renumbered to the No.

In 2016, HScott Motorsports closed down after the end of the season, leaving Addington a free agent.

38 car for RSS Racing in the Xfinity Series driven by C. J. McLaughlin and Parker Retzlaff.

19 car for Joe Gibbs Racing instead with Kyle Sieg, Ryan's brother, moving from RSS's No.

At age 14, Addington's mother remarried and then the family moved to Batesville, Arkansas where his stepfather began working for Mark Martin.

[citation needed] Although his stepfather worked in racing, Addington preferred to play football as a child.

Because the baby was about to be born around the time of the race at Talladega that month, Addington did not crew chief the No.