ARLINGTON -- The Rangers pulled off an unusual trade with the White Sox on Thursday so they could increase their pool of international slot bonus money.

The Rangers acquired catcher Welington Castillo and $250,000 in international slot money from the White Sox in exchange for Minor League infielder/outfielder Jonah McReynolds. Castillo was not with Texas for long, as the Rangers on Friday declined his $8 million option for 2020, allowing Castillo to become a free agent. Texas made the deal because the club covets more room to sign international amateur free agents next summer.

Castillo, a 10-year veteran, played in 72 games for the White Sox this past season and hit .209 with 12 home runs, 41 RBI, a .267 on-base percentage and a .417 slugging percentage. He signed a two-year, $15 million contract with the White Sox on Dec. 1, 2017, as a free agent, and he was suspended for 80 games during the '18 season for testing positive on Erythropoietin, a performance-enhancing drug.

McReynolds was a 13th-round pick by the Rangers in 2016 out of Patrick Henry (Va.) Community College who has spent the past three seasons at Class A Spokane.

Andrus expected to stay
The Rangers expect shortstop Elvis Andrus to remain with the team rather than exercising an opt-out clause in his contract. Andrus can elect to take his free agency this winter, but would be walking away from three years and $43 million left on his contract.

Texas also holds a $15 million option for 2023. That option becomes guaranteed if Andrus has 550 plate appearances in '22 or a combined 1,100 plate appearances in '21-22.

This is the second of two opt-out clauses Andrus had in his original eight-year, $120 million contact extension reached on April 4, 2013. Andrus, who also declined to opt out last offseason, has full no-trade protection, because he has a minimum of 10 years in the big leagues, including a minimum of five with the Rangers.

Rangers decline Kelley’s option
The Rangers declined reliever Shawn Kelley’s option for next season. They paid a $250,000 buyout rather than exercise a $2.5 million option.

Kelley pitched in 50 games for Texas this past season, going 5-2 with 11 saves, a 4.94 ERA and a 1.39 WHIP. He had a 3.09 ERA before the All-Star break and an 8.80 ERA in the second half while spending time on the injured list with a sore right bicep muscle.

The Rangers also declined a $3.75 million option on reliever Nate Jones. He was acquired from the White Sox on July 31 while on the injured list recovering from right elbow surgery. That deal was also made to acquire additional international slot bonus money.

Pence becomes free agent
With the end of the World Series, outfielder Hunter Pence officially became a free agent on Thursday. The Rangers have some interest in re-signing him this winter, but general manager Jon Daniels admitted that could be difficult given the surplus of outfielders on the 40-man roster.

The 40-man outfielders are left-handed hitters Nomar Mazara, Joey Gallo, Shin-Soo Choo and Willie Calhoun, right-handed hitters Delino DeShields and Scott Heineman and switch-hitter Danny Santana.

Pitcher Edinson Vólquez and infielder Logan Forsythe also became free agents on Thursday, but Volquez is expected to retire.

Granite, Biddle outrighted
Outfielder Zack Granite and left-handed reliever Jesse Biddle have been taken off the 40-man roster and outrighted to Triple-A Nashville. Both can become free agents on Monday.