After throwing 20 touchdown passes and just five interceptions in 15 games as a rookie, Griffin III threw 16 touchdowns and 12 picks in 13 games last season.
"What you saw last year was almost a little disrespectful to the game of football," Allen said. "It's impossible to ask a player to perform well during the regular season if you haven't practiced. Last year at this time, he was still rehabbing his knee, and he wasn't allowed to practice or work in team drills.
"We put him on the spot by trying to do that. And this year he's had a full offseason, his knee is 100 percent, knock on wood, and he's had all (the practices), and that's how you get ready to play a football season."
After winning the NFC East in 2012, Griffin had major knee surgery and the team struggled to 3-13 in 2013. Coach Mike Shanahan was fired at the end of the season and replaced by Jay Gruden.
One of Griffin's targets, wide receiver Pierre Garcon, left practice Monday with a hamstring injury, but it is not considered serious.
"He left practice early. He had a couple catches and then just had a little soreness in his hamstring. He'll be OK," Gruden said.