BOSTON -- The experimentation of outfield alignments officially began on Wednesday at Fenway Park, when Rusney Castillo made his debut in left field and handled the few chances he got in a 13-8 loss to the Yankees.
The Red Sox are comfortable in knowing that Castillo, Mookie Betts and Jackie Bradley Jr. should be their outfield trio going forward, perhaps for a few years. They've seen plenty to support that notion in recent weeks.
The club will use the final month of the season to gauge how the three best fit as a unit.
"It was an overall positive experience, especially being able to play it for the first time not just in the Major Leagues, but at Fenway Park," Castillo said through interpreter Adrian Lorenzo. "I felt pretty comfortable out there. I thought it went well."
Castillo was mainly a center fielder in Cuba, but he has looked comfortable in right during his time with the Red Sox. However, Bradley's cannon arm could play better in right at Fenway. Or Bradley could take over center with Betts and Castillo at the corners.
In recent days, Castillo has been doing early work in front of the Green Monster with outfield instructor Arnie Beyler.
Those sessions paid off in the second inning, when Chris Young belted one off the Monster, and the carom wasn't entirely true. Yet Castillo reached out at the last instant and snared it, holding Young to a single in the process. Castillo was credited with an assist once Brock Holt caught his throw and tagged out Brett Gardner, who wound up on third base at the same time as Stephen Drew.
"It was nice that I got to put into practice what we've been practicing with Arnie for the past few days or weeks," said Castillo. "It was nice to get it out of the way and get a play in. Thankfully it went OK."
What is the biggest difference Castillo sees between left and right?
The first thing that stands out is the depth that you play at," Castillo said. "You know that anything over your head is pretty much going to be off the wall, so you have to see how it bounces off.
"More than anything, playing at a different depth and knowing that everything is going to be in front of you and you're going to be coming in on everything as opposed to going back on the ball. That's a difference. It's a good thing Arnie and I have been doing a lot of work out there. He's hit balls at me every which way. I felt pretty good out there and comfortable by the time it was game time."
Given how gifted all three players are defensively, the Red Sox probably can't go wrong no matter which direction they end up going in.
"I thought [Castillo] did pretty good," said interim manager Torey Lovullo. "We had a quick discussion during the game with him. I asked him how he was going out there, [and] he said he felt comfortable and he felt good. All indications are showing that the work in progress will continue, but his first game is behind him, and I know he felt pretty good about how it turned out."
A year ago, Castillo was just getting used to life in the United States. Now, he seems comfortable in his surroundings and excited to be part of an outfield that has been creating excitement of late.
"I think we can do great things as a unit, as an outfield together, not only for the rest of the season, but for years to come," Castillo said.
The next step in the experiment will occur soon, when Betts plays one of the corner spots for the first time this year. Bradley has already played all three positions multiple times this season.
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, follow him on Twitter @IanMBrowne and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.