The Phillies may have lost Aaron Rowand after he signed a 5-year deal with the San Francisco Giants, but they haven't lost sleep or focus on where their offseason priorities lie. Improving the pitching. That's been the the Phillies' mantra since season's end. While the Phillies contest that the pickings are slim due to a mediocre free-agent pool, they know they have to bolster their staff if they have any chance to successfully defend their National League East title. A team source said yesterday that the Phils could be interested in righthander Akinori Otsuka, who was not offered a contract by the Texas Rangers before Wednesday night's deadline. Otsuka, 35, has 39 saves and 2.44 ERA over his 4 years in the majors. He opened the 2007 season as the Rangers' closer after tallying 32 saves with a 2.11 ERA in '06. But he wound up on the disabled list in mid-July and missed the second half of the season with right forearm inflammation. Rangers officials reported that he's had good rehab reports this winter.