The Kansas City Royals have reached an agreement with free-agent right-hander Zack Greinke on a one-year deal that will see him return for a 20th big-league season, the team has announced. The deal is for $8.5 million with the opportunity to earn up to $7.5 million more in incentives, reports Jon Heyman

Greinke, 39, returned to the Royals last season on a one-year free-agent contract. It was his first campaign with his original team since 2010. In 26 starts, he compiled a 3.68 ERA (111 ERA+) and a 2.70 strikeout-to-walk ratio despite posting the worst strikeout rate (4.8 per nine innings) of his big-league career. Greinke's contributions were worth an estimated 2.6 Wins Above Replacement, per the estimates configured by Baseball-Reference.

Though Greinke was successful from a results-based perspective, it was unclear if he would retire or return for another season. 

No ad available

Greinke's return to the Royals will technically serve as the third free-agent addition to their starting rotation this offseason. Earlier in the winter, new top executive JJ Picollo added Jordan Lyles and Ryan Yarbrough to the mix. Those two, plus Greinke, seem likely to be flanked by Brady Singer and either Brad Keller or Daniel Lynch heading into the new season. 

In addition to eight years (soon to be nine) with the Royals, Greinke has also pitched for the Milwaukee Brewers, Los Angeles Angels, Los Angeles Dodgers, Arizona Diamondbacks, and Houston Astros. He'll enter the season with career marks that include a 3.42 ERA (123 ERA+) and a 3.90 strikeout-to-walk ratio, as well as 71.5 Wins Above Replacement. 

No ad available

For those wondering, Greinke's total and peak WAR metrics put him on par with the average Hall of Fame starter. That doesn't mean he will actually be voted into Cooperstown when his career is over, but it puts him on the right track.