2. Francisco Liriano: 2013-present
When the Pirates signed Francisco Liriano before the 2013 season, they were signing a pitcher coming off a disastrous 2012 campaign. With the Twins and the White Sox, Liriano put up a 5.34 ERA, 4.34 FIP, and was worth -0.1 WAR.
I doubt many fans predicted big things for Liriano when he joined the Pirates, but all he’s done during his Pirates’ career is be one of the elite left-handed pitchers in all of Major League Baseball. So far he’s pitched to a 35-25 record with a 3.26 ERA, 3.23FIP, and has been worth 7.3 WAR in only three seasons with the team.
Liriano still has two seasons left on his current deal with the Pirates and if he continues on his current path, he could absolutely become the greatest free agent signing in team history; he’s probably already the best pitching free agent signing in team history. However in my opinion one signing is just a little bit better…