LAKE BUENA VISTA, Fla. – The Pittsburgh Pirates signed right-hander Charlie Morton to a three-year, $21 million contract extension Wednesday that could be worth up to $30 million, betting on the 30-year-old to continue a successful return from Tommy John surgery and hedging against the increasing price of starting pitching, sources told Yahoo Sports.

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Morton's extension represents the biggest deal given out at an otherwise-slow Winter Meetings and the largest for a pitcher in Pirates franchise history. He returned from reconstructive elbow surgery in June and posted a career-best 3.26 ERA over 20 starts and 116 innings, leading starters with a 62.9 percent groundball rate, the second-highest mark for any starter over the last five seasons.

"The most important part of this deal and the reason why this deal got done is Charlie wanted to remain a Pirate and considers himself a Pirate," said Morton's agent, Andrew Lowenthal of Jet Sports Management, who confirmed the deal to Yahoo Sports. "He loves the city. He loves the fans. The team stuck by him. This is Charlie's way of being loyal to the organization. The contract is a win-win."

Morton, who would have been a free agent following the 2014 season, will receive $4 million this season, $8 million in 2015 and $8 million in 2016. The contract includes a club option for the 2017 season worth $9.5 million with $500,000 in potential incentives and a $1 million buyout. Should Morton be traded, the club option turns into a mutual option. If triggered and Morton declined his end, he would forfeit the buyout.

The Pirates have a significant amount of salary flexibility going forward, with only National League MVP Andrew McCutchen and outfielder Jose Tabata signed beyond 2014. Morton will round out a rotation that for now includes Francisco Liriano, Gerrit Cole, Wandy Rodriguez and Jeff Locke. The Pirates continue to try to persuade starter A.J. Burnett to re-sign instead of retire.

Acquired in 2009 as part of the Nate McLouth trade, Morton has exceeded 116 innings just once, the year before he blew out his elbow. Still, scouts consider his two-seam fastball one of the best in baseball, a turbosinker he threw more than 70 percent of the time last season. With Pittsburgh's increased reliance on defensive shifts, a groundball pitcher such as Morton fits well with the Pirates' style.

"He was there through the lean years," Lowenthal said. "Now he wants to win a World Series with the Pirates.

"Bryan Stroh, the Pirates' general counsel, deserves a lot of credit for this. It had a lot of left turns and right turns. He stuck with it and made sure we came to a fair arrangement for both sides."

Teams continue to express incredulity at the price of free-agent starting pitching, and Morton’s deal represents the eagerness of clubs to avoid letting players reach the open market. This offseason, teams have spent nearly $200 million on starters, and arguably the four best pitchers of the class, Masahiro Tanaka, Ubaldo Jimenez, Ervin Santana and Matt Garza, have yet to sign.