One day shy of the one-year anniversary of having an elbow ligament reconstructed, Daisuke Matsuzaka returned to the mound today for the Red Sox. Relatively speaking, it went well. Five days after the Red Sox allowed Dustin Pedroia to play through a torn muscle in his right thumb, they're still waiting for their heart-and-soul second baseman to regain his All-Star form. Pedroia came to the plate with the tying run on base in the seventh inning and fouled out to first, killing the Red Sox' best chance for a comeback in a 4-2 loss to the Washington Nationals. He's 2-for-20 with a pair of singles since returning to the lineup, during which time the Red Sox have gone 1-4 and dropped back below .500 at 29-30. Before the game, manager Bobby Valentine admitted he didn't know what to expect from Matsuzaka, who hadn't started a major league game since May 16, 2011 against the Baltimore Orioles and underwent Tommy John elbow surgery on June 10 of last year. Through three innings, Matsuzaka couldn't have been much better. If there were any questions about Matsuzaka's health or mechanics, they were answered in the first inning when he fanned leadoff man Steve Lombardozzi on three pitches, got 19-year-old phenom Bryce Harper to fly to left field and fanned Ryan Zimmerman. After allowing a leadoff homer to Adam LaRoche on the first pitch of the second inning, Matsuzaka set down six consecutive hitters, three by strikeout. Trouble began in the fourth when Harper drew a leadoff walk, went to third on Zimmerman's single and scored on a ground-rule double by Michael Morse. One batter later, Ian Desmond notched a two-run single to give the Nationals a 4-0 lead. Nevertheless, Matsuzaka tossed a scoreless fifth inning before being lifted for reliever Franklin Morales. And for at least one turn in the rotation, he has stabilized the No. 5 starter spot, vacated last week when struggling Daniel Bard was sent to Triple-A Pawtucket.