This seems largely speculating based on his Spring Training numbers. Ishikawa currently has a .333/.467/.708 line in 24 at-bats this Spring. The most important number there is that we're only talking about 24 at-bats. A lot of those at-bats have come against Triple-A guys later in the game, after all of the starters left the game. Meanwhile, Lambo is 4-for-42. Those aren't good numbers, but to put them in perspective, they basically represent one to two horrible weeks during the regular season.
Ken Rosenthal seems to think that the Pirates are still looking at Lambo and Ishikawa, and won't go for someone like the recently available Juan Francisco.
Tim is the owner and editor in chief of Pirates Prospects. He started the site in January 2009, and turned it into his full time job during the 2011 season. Prior to starting Pirates Prospects, Tim worked with AccuScore.com, providing MLB, NHL, and NFL coverage to various national media outlets, including ESPN Insider, USA Today, Yahoo Sports, and the Wall Street Journal. He also writes the annual Prospect Guide, which is sold through the site. Tim lives in Bradenton, where he provides live coverage all year of Spring Training, mini camp, instructs, the Bradenton Marauders, and the GCL Pirates.