ANAHEIM -- The Mariners moved to bolster their bullpen on Friday, acquiring 25-year-old right-hander Sam Tuivailala from the Cardinals for young pitching prospect Seth Elledge.
Tuivailala is expected to join the team for Sunday afternoon's series finale against the Angels, so no roster move will be needed to clear a spot for him until then.
Mariners general manager Jerry Dipoto used a promising future reliever to acquire a current contributor for this year's playoff push, though Tuivailala has four years of team control remaining and isn't just a short-term addition.
"Sam is in the midst of his second consecutive solid big league season and has pitched in parts of four Major League seasons, but has barely two years of service time," Dipoto said. "We view this as a move for our present and our future."

Tuivailala is 3-3 with a 3.69 ERA in 31 2/3 innings over 31 games this season. He made his Major League debut as a 21-year-old with the Cardinals in 2014 and has pitched in 96 games for St. Louis over the past five seasons, with a 3.65 ERA and 88 strikeouts in 98 2/3 innings.
"I'm excited to see him," said manager Scott Servais. "I've heard a lot about him and we'll see where he fits in. He's got good stuff. A fastball up to 98 [mph] and he usually pitches more 95-96. A younger player, very athletic guy. He's done very well against right-handed hitters, which will serve him well."
Elledge was Seattle's No. 10 prospect inthe latest MLB Pipeline rankings. The 22-year-old was drafted in the fourth round out of Dallas Baptist last year and has posted a 1.17 ERA in 31 games for Class A Advanced Modesto this season.
Tuivailala figures to bolster the middle-relief crew for Seattle, which currently holds a one-game lead over Oakland in the chase for the American League's second Wild Card berth. The Mariners are 61-41 with 60 games remaining.
The Mariners have lost nine of their past 14 games heading into a three-game series in Anaheim this weekend.
Tuivailala was drafted by the Cardinals out of Aragon High School in San Mateo, Calif., in 2010 and spent his first two seasons as a position player before being converted to a reliever as a 19-year-old in 2012. He moved quickly through the Cardinals' Minor League system and posted a 7-3 record and 2.97 ERA with 42 saves in 108 games at the Triple-A level.

This has been his first full season in the Majors and he's excelled against right-handed hitters (.230/.247/.284 with 18 strikeouts and one walk over 79 plate appearances), while struggling against lefties (.333/.446/.556 with eight strikeouts and 10 walks over 65 plate appearances).
Though his career numbers aren't nearly as platoon-heavy, the Mariners figure to use Tuivailala primarily as a right-handed specialist to help get games to All-Star closer Edwin Diaz. Dipoto already acquired former Rays closer Alex Colome two months ago and has Juan Nicasio, Nick Vincent and Chasen Bradford as other right-handers, along with lefties James Pazos and Roenis Elias.
"He'll be one of those bridge-the-gap type guys," Servais said. "And then days when we're running Nicasio and Colome really hard and need to give them a day, you've got the Vincents and guys like Tui that we can slide right in there."