The two sides agreed in principle to a two-year, $12.75 million contract in late December, but a Major League source told MLB.com earlier this month that Liriano suffered an injury to his non-throwing right arm shortly after the deal was agreed upon, thus taking it off the table.
According to Rosenthal's report Monday, the deal has been adjusted and Liriano will assume risk due to the injury. The Pirates have not confirmed the signing.
The southpaw is coming off a 6-12 season (34 total appearances, 28 starts) split between the Twins and the White Sox, to whom he was traded July 28. He has a career record of 53-54, including seasons of 12-3 in 2006 and 14-10 in 2010, both with Minnesota.
Liriano is expected to fill a spot in the middle of the Pittsburgh rotation, behind A.J. Burnett and left-hander Wandy Rodriguez and ahead of James McDonald.