Liriano, 28, pitched seven seasons for the Twins, posting a 4.33 ERA with 788 strikeouts in 783 1/3 innings.
He had a 5.31 ERA with 109 strikeouts and 55 walks in 100 innings with the Twins this season, but he's been pitching better recently with a 3.68 ERA, with 79 strikeouts in 66 innings over his last 12 outings dating back to May 30 after a stint in the bullpen due to early-season struggles.
"He was a lot of fun, and he's been a standup guy for this organization for a long time," Twins manager Ron Gardenhire said. "He hasn't ducked away from too many things. We all know about his struggles; we also know he's been one of the more dominant pitchers when he's on, that we've had around here. He can do a lot of fun things -- no-hitters, striking out 15-plus, whatever. Those are all the fun times; the tough times are when he couldn't find it. No one felt worse than him; he was a team guy."
Liriano had indicated in recent weeks that he enjoyed playing in Minnesota, but neither his agent nor the Twins pursued a contract extension, according to general manager Terry Ryan. Liriano said it was tough to part ways with the Twins, who originally acquired him via a trade with the Giants in 2003.
"It's kind of sad, but it's not my call, so there's nothing I can do about it," said Liriano in a conference call. "It was kind of a surprise to me, but that's part of baseball."
Liriano added that it was strange hearing that he'd be headed to a division rival. He'll make his first start against his former team on Tuesday with the White Sox at Target Field during a three-game series starting Monday.
"I knew something like that might happen, but not to the White Sox," Liriano said. "It is what it is. They're a good team, they're in first place; I'm very excited to go out there and help them win some ballgames."
Liriano had his fair share of big moments -- such as his no-hitter against the White Sox last year and his 15-strikeout game against the A's on July 13 -- but also struggled with his consistency.
He burst onto the scene in 2006 with a 2.16 ERA with 144 strikeouts in 121 innings, but after the season ended up needing Tommy John surgery, which kept him out until 2008.
Since the surgery, he's seen his ERA fluctuate over the years, with a 3.91 ERA in '08, 5.80 in '09, 3.62 in '10, 5.09 in '11 and 5.31 ERA this year.
When asked to describe Liriano's career with the Twins, pitching coach Rick Anderson called it "up and down."
"You've seen very, very good Frankie at times, and you've seen a Frankie that struggles," Anderson said. "We said it a million times -- he's got some of the best stuff you'd want to see. It's just a matter of putting it all together."
Twins first baseman Justin Morneau said Liriano's stretch in '06 was the best he'd ever seen by a pitcher, including former teammate and two-time Cy Young Award winner Johan Santana.
He said it was tough to see Liriano go, but understood that the team has to build for the future, as they're 14 games back of the White Sox in the American League Central and Liriano was set to be a free agent after the season.
"It's disappointing," Morneau said. "He's a guy, as far as stuff-wise, can match up with anybody in the league. We've seen him as good as anybody in baseball. I was up here in '06 and saw the run he was on, and when he got hurt. I think he was trying to find that ever since. We've seen him brilliant at times -- the no-hitter, the big strikeout game he had a couple starts ago. He was a guy that was a very good teammate, very good in the clubhouse. It's tough to lose a guy like that."
Catcher Joe Mauer, who caught Liriano 85 times dating back to '05, agreed with Morneau and said Liriano's presence in the clubhouse will be missed.
He added it's tough to see the Twins act as sellers before the Trade Deadline, as it's been a rare occurrence for the team that has won six division titles dating back to 2002.
"Obviously, it's not a good feeling," Mauer said. "It's what happens when you're not winning and you're not doing well. You have to make changes. We lost not just Frankie, but a few other good people the last few years, and it's been tough."