Pittsburgh (KDKA/AP) – The Pirates added another pitcher to their staff on Thursday. They have claimed LHP Aaron Thompson off waivers from the Washington Nationals.

To make room for Thompson on the 40-man roster, the Pirates designated LHP Wil Ledezma for assignment. Ledezma pitched in 26 games with a 6.86 ERA for the Pirates in 2010. He threw in 19 1/3 innings, giving up 25 hits, 16 runs and striking out 22.

Thompson came to the Nationals in the July 2009 trade-deadline deal that sent Nick Johnson to the Florida Marlins.

This past season, Thompson went 4-13 with a 5.80 ERA in 26 starts at Double-A Harrisburg. He pitched in 136 2/3 innings, giving up 164 hits. Thompson struck-out 95, walked 53 and gave up 96 total runs with Harrisburg.

Thompson moved up to Triple-A Syracuse for one game last season recording the win.

Pittsburgh also signed infielder Garrett Atkins to a minor league contract with an invitation to spring training as a non-roster player.

Garrett is an eight-year major league veteran and spent this past season with Baltimore following seven seasons with Colorado.

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