According to NFL.com, 20 teams were on hand for Iowa's pro day. I don't know if the Green Bay Packers were in attendance, but they should have been. While it's not an absolute necessity to draft a defensive end in the first round to replace DE Cullen Jenkins when he leaves in free agency, they do have to add some depth at some point.
DE Adrian Clayborn has an explosive first step, but he's also battled Erb's Palsy nearly his entire life, and it limits his shoulder motion. He always seemed around the play when he was with the Hawkeyes, and he's one of the few defensive ends in the draft that could replace Jenkins's explosive inside pass rush. Unfortunately he won't last until the end of the first round.
DE Christian Ballard looks like a solid player, and I've seen at least one mock draft with the Packers selecting him, but he doesn't look like a big playmaker. He'd be valuable in the defensive rotation, and I'm not too interested in him as a first round pick.
DE Karl Klug is not someone who dazzles at an NFL combine workout, but he was another guy who was always around the ball with the Hawkeyes. He'd be a steal as an undrafted free agent, and a solid selection as a late round pick.