The Pirates traded their fourth outfielder Tuesday, sending Travis Snider to the Baltimore Orioles for minor league left-handed pitcher Stephen Tarpley and a player to be named later.

By trading Snider, the Pirates sent away a productive hitter and an insurance policy for right fielder Gregory Polanco, who will be entering his first full year in the major leagues.

"That's a little bit of discomfort that goes along, those are the challenges that small-market clubs have to [face]," general manager Neal Huntington said. "Every time, you've got to keep an eye on the future."

Snider, who turns 27 Monday, hit .264 with a .338 on-base percentage and 13 home runs last season. He set career highs with 359 plate appearances and 140 games. In the second half of the season, he hit .288 with nine home runs, a .356 OBP and a .524 slugging percentage.

Polanco started well after his debut in early June, but hit .219 with a .276 on-base percentage in July and August. The Pirates optioned him to the minors briefly before rosters expanded in September.

"We were not intending to move [Snider]," Huntington said. "We felt like he was a really good fit on our club."

Andrew Lambo and Jose Tabata are candidates to fill the fourth-outfielder role. Lambo, 26, is a left-handed hitter who hit .328 in 61 games at Class AAA Indianapolis last season. He is on the 40-man roster. Tabata, 26, who bats right-handed and hit .282 with a .314 on-base percentage in 186 plate appearances in the majors last year, is not on the 40-man roster.

Corey Hart, 32, also could play right field. A right-handed batter, Hart played right field most of his career before moving to first base in 2012, but surgeries on both knees forced him to miss the entire 2013 season.

"We've got any number of guys that could step up and compete and fill that role," said Huntington, who also mentioned Sean Rodriguez and Josh Harrison as possibilities.

The Orioles had interest in Snider at least as far back as the winter meetings in December, when the teams discussed a trade that would have brought left-handed pitcher Brian Matusz to the Pirates. Instead, the Pirates got Antonio Bastardo from the Philadelphia Phillies to fill their need for a left-handed reliever.

Huntington said the Pirates traded from an area of depth and added flexibility, both on their roster and financially. Snider had avoided arbitration with a $2.1 million contract for 2015. He has one more year of arbitration eligibility remaining before reaching free agency.

Tarpley, 21, had a 3.68 ERA in 13 games, 12 starts, with short-season Aberdeen in 2014. He struck out 60 batters, walked 24 and had a 1.41 WHIP in 66 innings. The Orioles selected Tarpley in the third round of the 2013 draft out of Scottsdale Community College.

"Tarpley is an athletic, young left-handed pitcher with good stuff, chance to start, starter indicators," Huntington said. "Throws strikes, gets ground balls, gets some swing-and-miss."

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NOTE -- Root Sports will televise five spring training games this season, including the exhibition against Philadelphia at 7:05 p.m. April 3 at Citizens Bank Park. They will televise one other night game, March 18 against Detroit Tigers at 6:05 p.m. The rest of the games to be broadcast -- March 15 against the Orioles, March 17 against Houston and March 21 against Boston -- begin at 1:05 p.m.

Bill Brink: bbrink@post-gazette.com and Twitter @BrinkPG.

First Published: January 28, 2015, 2:48 a.m.