The Redskins head coach told reporters: "Rex is a great guy, a natural leader. He did a good job for us when we didn't have a lot of depth and a lot of talent. I just like the way he handles himself. When he does play, he's played well."
Griffin added: "Experience is one thing you can't buy and he's experienced a lot throughout his career, from Super Bowls to everything in between.
"Rex has been a great guy to have on this team. He's a great locker-room guy, a great meeting-room guy, and he has really helped me with how to handle a lot of things."
Grossman led the Bears to the Super Bowl in the 2006 season, but lost the starting job early in the 2007 season and left the team at the end of the following year.