The Denver Broncos were busy on the first day of the NFL’s free agency period, adding a piece to an already stout offensive line. The Broncos agreed to terms on a four-year contract with Louis Vasquez, formerly of division rival San Diego. Vasquez started all 16 games at right guard for the Chargers last season and has made 54 starts in his four-year career. The 335-pounder will likely fill the right guard slot for the Broncos, as concerns abound over the health of incumbent starter Chris Kuper. Kuper has had multiple ankle surgeries since suffering a gruesome ankle dislocation in 2011. Denver’s deal with Vasquez is reportedly worth $23.5 million, including $13 million guaranteed. The Broncos also brought back defensive tackle Kevin Vickerson on a two-year contract, and will resume negotiations on a restructuring of defensive end Elvis Dumervil’s deal.