CINCINNATI — The Miami Marlins didn't know when spring training began whether Caleb Smith would be a better fit as a starter or as a left-hander out of the bullpen. Right now, he's as good as they've got in the rotation.

Smith gave his third straight impressive performance Saturday night, and Starlin Castro drove in three runs with a homer and a double, leading Miami to a 6-0 victory over the Cincinnati Reds.

The Marlins will try to win their fourth straight series on Sunday.

Miami got Smith (2-3) from the Yankees in the offseason as part of a deal for right-hander Michael King. The left-hander has been stingy in his last three starts, allowing only two runs and seven hits in 18 2/3 innings with 26 strikeouts.

"I feel like a kid," said Smith, who made two starts and seven relief appearances for New York last season. "It's awesome."

Against the Reds, he gave up three hits and fanned seven in 5 2/3 innings, escaping threats created by a couple of Marlins errors. Three relievers completed a four-hitter.

Smith had a couple rough starts in April. Marlins coaches talked to him about throwing more strikes and challenging hitters, and it's made the difference.

"He was OK in spring training," manager Don Mattingly said. "We thought he deserved an opportunity to see what he could do. It was his time. We had an opportunity to find out whether he'd be a starter or a reliever. Right now, he's a starter."

Miami's struggling offense got the early lead with a pair of homers off rookie Tyler Mahle (2-4). Martin Prado doubled in the first and Castro followed with his 100th career homer . Justin Bour added a solo shot in the sixth inning, his team-leading sixth homer.

"I didn't really settle in," Mahle said. "The one pitch they got to hit they hit well, but I continued to make just average pitches."

Castro's RBI double started a three-run rally in the eighth. Brian Anderson singled home two more.

Miami's J.T. Realmuto went 0 for 3 and was hit by a pitch, ending a 12-game hitting streak that was the longest active in the NL.

The Reds fell to 8-25, matching the second-worst start in club history from 1934. They were shut out for the fifth time, tied with Miami for second-most in the NL behind Milwaukee.

WHAT'S UP DOC?

Mattingly received an honorary Doctor of Humane Letters degree from the University of Evansville. Evansville President Thomas A. Kazee traveled to Milwaukee when the Marlins played there last month to privately present the degree , which was announced Saturday as part of the school's commencement.

Mattingly grew up in Evansville, and two brothers attended the school. He went into the Yankees' organization after high school.

"I'm excited about it," Mattingly said. "I had two brothers go to that school, so since I was a kid I would go to their games."

CASTRO'S PLACE

Castro's first homer in the majors also came at Great American Ball Park. He homered in his first big league plate appearance off Homer Bailey on May 7, 2010, with the Cubs.

SLIGHT DELAY

The game started 10 minutes late because of rain, which fell steadily through the early innings.

SCOOTER BACK

Second baseman Scooter Gennett was back in the Reds' lineup after being limited to pinch-hitting in the previous four games because of a sore throwing shoulder. He went 0 for 3 with pair of strikeouts.

TRAINER'S ROOM

Reds: RHP Michael Lorenzen threw 40 pitches without problem at the Reds' spring training complex. He has been sidelined since the start of the season with a strained pitching shoulder. He's scheduled to throw batting practice on Monday.

UP NEXT

Marlins: Dan Straily (0-0) makes his second start since returning from an inflamed right forearm. He has lost both of his career appearances against his former team.

Reds: LHP Brandon Finnegan (0-2) has been the victim of blown saves in each of his last two starts. The Reds have lost all of his four starts this season.