The Giants on Saturday claimed Castillo off waivers, clearing the way for Jorge Cantu to win the Marlins' starting third-base job.
Unsure how Castillo, 27, would handle a reserve role, the Marlins placed the Venezuelan native on waivers on Thursday. The waiver window allows 72 hours for a player to be claimed by another club.
"He did a great job in camp," said Larry Beinfest, the Marlins president of baseball operations. "Our feeling was Jorge Cantu had a leg up on the competition. We put Jose on waivers to gauge other interest. We were unsure how effective he would be in a part-time or bench role. We are hopeful this is a better opportunity for him."
The Marlins opened Spring Training with three primary third-base candidates: Castillo, Cantu and Dallas McPherson. The position became vacated after Miguel Cabrera was traded last December to the Tigers.
While the club wasn't looking for any of the three to replace Cabrera's incredible offensive numbers, they have been looking for solid defense as well as offensive production.
Castillo, who spent four seasons with the Pirates, signed as a free agent for $650,000 on Dec. 24. He has played terrific defense and is batting .275 for the spring with four doubles, a home run and six RBIs.
"I came to the Marlins trying to play good defense," Castillo said. "It was a good experience for me. I want to thank the Marlins. Right now, I'm happy that I have a job and that I have an opportunity to play."
Castillo actually was in uniform and ready to play on Saturday when the Marlins visited the Orioles in Fort Lauderdale. The game was delayed by rain before being canceled. He was in the clubhouse when he was informed that he was headed to the Giants.
The play of Cantu made Castillo expendable.
A non-roster invitee, Cantu has posted outstanding Grapefruit League numbers, batting .431 with 22 hits.
Beinfest noted that the final roster is not set, but with Castillo now gone and given that McPherson has missed substantial time due to a couple of ailments,Cantu is the overwhelming frontrunner to be at third base in the March 31 opener against the Mets at Dolphin Stadium.
Beinfest praised Cantu's defense and noted that his offensive productivity speaks for itself. The way Cantu is playing now reminds many within the organization of how he performed in 2005 with Tampa Bay, when he belted 28 home runs and drove in 117.
McPherson, meanwhile, has an outside chance to win a roster spot. The left-handed hitter, who has been slowed by an oblique problem and, more recently, a groin pull, was slated to be the designated hitter on Saturday. It would have been his first Grapefruit League action in weeks.
Barring any unforeseen pickups, the Marlins plan on going with Cantu as their primary third baseman, with slick-fielding Alfredo Amezaga as a defensive option for late innings. Jason Wood, who also plays both corner positions, could once again win a roster spot as a situational player at first base or third.
Joe Frisaro is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.