MINNEAPOLIS -- Boston Red Sox catcher Blake Swihart might know better than anyone else what to expect from the 22-year-old Eduardo Rodriguez when the lefty makes his MLB debut against the Texas Rangers on Thursday night. Swihart caught Rodriguez in the minors last season and said there definitely won't be a lack of confidence in his debut.

"He's a competitor," Swihart said. "He's going to come out and compete. He thinks he's going to get the guy out whenever he's on the mound. That's what we want."

Rodriguez was acquired from the Baltimore Orioles last season as a part of the Andrew Miller deal. Though he's still a little rough around the edges, Rodriguez has showed good stuff in his time in Triple-A Pawtucket this season. He's currently 4-3 with a 2.98 ERA to go along with 44 strikeouts.

Red Sox manager John Farrell spoke highly of Rodriguez before Wednesday's game.

"He's got very good stuff," Farrell said. "He's got very good ability with his fastball -- a lot of strikes, a lot of power to it. His changeup is a true weapon for him. His slider is a pitch for him that continues to come along. We wanted to build in an extra day for guy. We also wanted to get his debut kind of under his belt before we could possibly need him later this season."

It's likely Rodriguez will be sent back down to Triple-A Pawtucket following the spot start.

Castillo's brief absence: Rusney Castillo missed Wednesday's series finale against the Minnesota Twins after jarring his shoulder while making a diving grab in Tuesday's loss. Castillo doesn't see it as an injury that will keep him out long term, though.

"It's tough to say exactly," Castillo said via a translator after the 6-4 loss to the Twins. "We're going day-by-day right now. I was ready to go in today. I wouldn't have been 100 percent, but I did feel much better as the day went on."

Castillo said he hopes to play Thursday night against the Texas Rangers.