Cartwright played 10 years in the NFL, spending eight of those seasons with the Washington Redskins. A former seventh-round pick back in 2002, Cartwright ran for 956 yards and six touchdowns in his career. He didn't officially retire from the NFL until 2014.
His last season in the NFL was in 2011 with the Oakland Raiders; he carried the ball only four times for 45 yards.
The last time Cartwright was involved with the NFL, he was opposing it. He was one of the seven former NFL players who filed a formal objection to the league's attempted concussion settlement back in July 2014.
Now, it seems Cartwright is back in the NFL and wants to begin a path toward coaching. ESPN.com's Jeff Legwold, who once wrote for the Denver Post, explained in this 2011 Q&A what the roles and duties of the quality coach are:
They do have some on-field duties in practices, often they work with one or more position coaches to gain experience as they prepare to become position coaches themselves. Callahan, for example, was the Broncos' running backs coach for the final month of the season after Eric Studesville was promoted to interim coach.
But overall, a quality control assistant's job is rooted in game preparation. They usually work at least one or two weeks ahead in the regular season.
They prepare the statistical analysis as well as the initial video study of upcoming opponents. The defensive quality control assistant breaks down opposing offenses, including how often they line up in specific formations and how they use various personnel groupings.
Cartwright working with the offense could mean he'll be focused primarily on the running backs. At least he'll have a quality offensive mind to learn from in new head coach Hue Jackson.