The 2012 rookie of the season struggled in his second year in the NFL, having undergone surgery to repair a double knee ligament tear last January.
The Washington Redskins' offensive coordinator told ESPN Radio: "I don't think there's any question, he looks explosive.
"He looks like he is exactly what he was in the 2012 season. I think people underestimate when you have a brace on your knee how much that truly restricts you. So I think being able to take that off, he looks extremely explosive.
"And when you're a quarterback that has the ability to kind of buy time with your legs, keep your eyes downfield and then if guys are playing with their back to the quarterback, now he's got a chance to take off and run it and create yards that way. So I think that's going to be a big part of what he does."
Griffin featured in 13 games for the Redskins last season before being benched for the final three, completing 3,203 passing yards and 16 touchdown passes.