The Pirates haven't confirmed the transaction. A source with knowledge of the situation told MLB.com that the deal was close to being final, pending a physical that would likely be taken after Christmas.
Liriano, 29, was 6-12 with a 5.34 ERA in 34 games, including 28 starts, for the Twins and White Sox last season. He spent most of his career with Minnesota and had his best year during an All-Star 2006 season when he was 12-3 with a 2.16 ERA.
Unfortunately, that nice season was shortened by a torn elbow ligament and Liriano missed all of 2007.
In 2010, Liriano was named the American League's Comeback Player of the Year winner. On May 3, 2011, vs. the White Sox, he threw a no-hitter during a 1-0 victory.
On July 28 of last season, the Twins traded Liriano to the White Sox for two Minor Leaguers.
In 168 career games, Liriano is 53-54 with a 4.40 ERA.