Kansas City, Mo. ? Left-hander Bruce Chen got his wish Thursday, agreeing to a $4.25 million, one-year contract to return to the Kansas City Royals, where he has spent the past five seasons.

Chen became a free agent after last season, but he made it clear that he wanted to return to the Royals. He’ll do so on a deal that pays $3.25 million this season with a mutual option at $5.5 million for 2015 with a $1 million buyout. The deal is subject to a physical, likely to take place today.

He’ll also be eligible for performance bonuses this season of $125,000 for each start from 16 through 25, a sign the Royals may view him primarily as a long-reliever with the ability to step in as a spot starter in the case of injuries or ineffectiveness.

That’s similar to the role Chen had last season, arguably the best of his 15-year career. He went 9-4 with a 3.27 ERA while making 15 starts and 19 appearances out of the bullpen.

One of the most popular players in the clubhouse, the 36-year-old Chen has seemingly gotten better with age. He won 35 games for the Royals from 2010-12, when he was almost exclusively a starter, and then helped stabilize the rotation the last 21/2 months of last season.

Chen’s been successful despite a fastball that rarely breaks 85 mph. He instead relies on a beguiling mix of sliders, curveballs and cutters, and often jokes about his lack of velocity.

The front end of the Royals rotation is set with James Shields, Jeremy Guthrie and recently signed Jason Vargas. Talented left-hander Danny Duffy, who came back from Tommy John surgery last season, is in line for one of the remaining spots, leaving the fifth job up for grabs.

Hard-throwing youngster Yordano Ventura pitched well during a September call-up and is widely expected to join the rotation at some point this season. It’s possible that Chen could serve as a stopgap out of spring training if Ventura isn’t quite ready to step into the rotation.

Former starter Luke Hochevar, who flourished in the bullpen last season, and Wade Davis, who has also been much better as a reliever than a starter, could also compete for the job.