The Arizona Diamondbacks acquired left-handed reliever A.J. Puk from the Miami Marlins on Thursday night, the first major trade of a deadline season that has been slow due to a lack of teams unloading players, sources told ESPN.

Miami, one of the few teams expected to be busy subtracting from its major league roster before the July 30 trade deadline, will receive slugging infielder Deyvison De Los Santos and center fielder Andrew Pintar in the trade, source said.

Puk, 29, began the season in the Marlins rotation as they tried to transition him back to a starting pitcher after two excellent years in the bullpen. He returned to a relief role in mid-May and has been one of the most effective pitchers in baseball since, posting a 2.08 ERA with 33 strikeouts in 30.1 innings and an opponent slash line of .159/.204/.252.

Arizona, the defending National League champion, is 53-50 and one game back of the third wild-card spot. The Diamondbacks’ bullpen in particular has struggled, with the lowest strikeout rate in MLB with 7.39 per nine innings and the 22nd-lowest ERA at 4.24.

Puk will join closer Paul Sewald, right-handers Justin Martinez, Ryan Thompson, Kevin Ginkel and left-hander Joe Mantiply as Arizona’s main bullpen options. The Diamondbacks’ rotation soon should be fortified, too, with the expected returns of right-hander Merrill Kelly and left-hander Eduardo Rodriguez from shoulder injuries next month.

The Marlins, who are expected to move closer Tanner Scott and could also trade center fielder Jazz Chisholm, first baseman Josh Bell, left-hander Trevor Rogers and others, receive an elite power bat in De Los Santos, whose exit velocities rank among the highest in the sport.

De Los Santos has spent more than half the season at AAA despite just turning 21 and has hit 28 home runs at in 372 plate appearances AA and AAA this season. He has played mostly first base this year, though he spent previous seasons taking a majority of his reps at third base.

While De Los Santos’ eye at the plate is perhaps the biggest question about his long-term ceiling as a big league, Pintar has no such issues. Drafted in the fifth round out of BYU in 2022, he was recently promoted to AA after hitting .304/.403/.516 at AA. While he was a middle infielder in college, Pintar moved to center and has acquitted himself well with the speed that has allowed him to steal 18 bases in 19 attempts this season.