Nationals Notes: Madson, Hernandez, Norris

The Nationals are looking to return to the .500 mark for the first time since 2005, their inaugural season in Washington. Here's the latest on the team:

• Ken Rosenthal of FOX Sports suggests the Nationals might become serious bidders for Ryan Madson if the Phillies don't lock the closer up.
• Nationals GM Mike Rizzo joined Jim Bowden on MLB Network Radio and said he’s still looking for a center fielder (all Twitter links via MLB Network Radio). The Nationals will "probably" trade from minor league or Major League depth for a center fielder, Rizzo said. The GM added that the Nationals are set at second, shortstop and first.
• The Nationals expressed interest in B.J. Upton, Denard Span and others over the course of the summer and Bowden suggests the Twins are a possible trade partner again (Twitter link).
• Free agent right-hander Livan Hernandez won't return to the Nationals, according to Rosenthal, who won't be surprised if the Marlins turn to Carlos Zambrano or Hernandez if their pursuit of Mark Buehrle comes up short. MLBTR's Tim Dierkes rounded up all of the latest Marlins rumors earlier today.
• The Nationals must place catcher Derek Norris on the 40-man roster or risk losing him in the Rule 5 Draft, according to Amanda Comak of the Washington Times. The Nationals now have 32 players on their 40-man roster, so there’s room for Norris, who hit .210/.367/.446 at Double-A in 2011.