HOUSTON -- With the Mariners making a push in the American League Wild Card race, general manager Jerry Dipoto reinforced his bullpen Thursday by trading four Minor Leaguers to the Marlins for veteran reliever David Phelps.
The Mariners gave up 19-year-old outfielder Brayan Hernandez, who was their No. 6-ranked prospect, per MLBPipeline.com, as well as right-handed pitchers Brandon Miller, Pablo Lopez and Lukas Schiraldi. Miller was Seattle's No. 16 prospect and Miller was No. 22.
Hernandez was one of the top prospects out of the 2014 international class from Venezuela when he was given a $1.85 million signing bonus by the Mariners, and he's regarded as a promising five-tool player currently competing for Class A Short-Season Everett.
In return, Seattle received immediate help, as Phelps was one of the most sought-after setup relievers available on the market, and he will strengthen a bullpen that already had the lowest ERA in the Majors over the past 51 games at 2.65.
"David was a target player for us headed into the Deadline period," Dipoto said. "The quality of his work, particularly over the past two years in the bullpen, in addition to his versatility -- including his background as starter -- made him very attractive to us. He fits our roster very well and is controllable through the 2018 season."

Phelps, 30, was 2-4 with a 3.45 ERA in 44 appearances with the Marlins this season, including a 2.19 ERA and a .195 opponent's batting average in his past 36 games.
Phelps is earning $4.6 million and will be arbitration-eligible this offseason before becoming a free agent following the 2018 season.
Phelps went 20 innings without allowing an earned run from April 21 to June 7, and he entered Wednesday ranked ninth among all National League relievers in innings pitched and tied for second in holds with 18.
With the Astros running away with the AL West, the Mariners are chasing a Wild Card berth, and they sit 1 1/2 games back of the Yankees for the No. 2 spot heading into a four-game series with the Bombers starting Thursday at Safeco Field.
Young Mariners closer Edwin Diaz has been on a strong roll recently, with five saves in Seattle's past six games, while Nick Vincent, Steve Cishek, Tony Zych and lefty specialist Marc Rzepczynski have also pitched well.
But Vincent and Diaz both threw in five of the past six games, and Phelps should help take some of the pressure off that back-end group. Phelps was outstanding as well in 2016, when he went 7-6 with a 2.28 ERA with four saves, 25 holds and 11.8 strikeouts per nine innings over 86 2/3 frames in 64 games.
Phelps is a six-year Major League veteran who debuted with the Yankees in 2012 and was traded to Miami before the '15 season. He's 28-32 with a 3.90 ERA in 218 games, including 64 starts.
With the Trade Deadline still 11 days away, Dipoto likely isn't done. The Majors' most active GM is still pursuing rotation help as well to bolster a group that lost lefty Drew Smyly for the season following Tommy John surgery. Veteran right-hander Hisashi Iwakuma's status is also uncertain, as he's missed two months with a shoulder issue, leaving Seattle with two rookies -- Andrew Moore and Sam Gaviglio -- in its current five-man group.
Hernandez hit .252 with two home runs and 15 RBIs in 28 games with Everett, and he also appeared in three games for Triple-A Tacoma, going 2-for-5.
Miller, 22, went 9-4 with a 3.65 ERA in 18 starts for Class A Clinton this season after being drafted in the sixth round last year out of Millersville University.
Lopez, 21, was 5-8 with a 5.04 ERA in 19 games (18 starts) with Class A Advanced Modesto. He signed with Seattle as an international free agent in 2012, but he missed the '14 season following Tommy John surgery.
Schiraldi, 24, had a 4.58 ERA in 28 relief appearances for Modesto. He was a 15th-round Draft pick out of Texas in 2014 and is the son of former big league pitcher Calvin Schiraldi.