Pedro Alvarez hit a three-run homer and had four RBI as the Pittsburgh Pirates completed a three-game sweep of the Chicago Cubs with a 10-4 victory in the finale yesterday at PNC Park. Starlin Castro ripped a two-run homer and Darwin Barney added an RBI double for the Cubs, who have lost 12 straight and are just two losses shy of tying a franchise-worst 14-game skid. Matt Garza was tagged for six runs, five earned, in five-plus innings to absorb the loss. The Northsiders return to Wrigley Field this afternoon to open up a three-game homestand against the San Diego Padres. Travis Wood will toe the rubber opposite Jeff Suppan in the opener.