Packers General Manager Ted Thompson is intent on improving the team's defensive line.  On Wednesday, Thompson signed former Miami Dolphins defensive end Phillip Merling after an underachieving four years in South Florida.  Merling was the first pick of the second round out of Clemson in the 2008 NFL draft.   His rookie year was highlighted by scoring a touchdown on an interception of Brett Favre who was with the Jets, denying New York a playoff berth on the final day of regular season.  After playing all 16 games in 2009, Merling (6-5, 315) tore his Achilles' tendon after just five weeks.  He returned to the team last season but was released earlier this spring.  Merling joins the free agent class that includes Anthony Hargrove and Daniel Muir.   Thompson also drafted a pair of defensive linemen in Jerel Worthy and Mike Daniels.