The Oakland Athletics acquired left-handed reliever Jake Diekman from the Kansas City Royals on Saturday, bolstering a bullpen already considered among the most talented in baseball.

The well-traveled Diekman, 32, joined the Royals as a free agent this winter and had been one of the most popular players on the trade market leading up to the July 31 deadline because of his coveted fastball-slider mix.

Oakland pounced and will send prospects Dairon Blanco, an outfielder, and right-handed pitcher Ismael Aquino to Kansas City.

Entering Saturday's games, Oakland (58-47) is eight games behind the Houston Astros in the American League West. The Athletics, however, are tied with the Boston Red Sox for third place in a heated wild-card chase -- just a half-game behind the Tampa Bay Rays for the final spot.

While Diekman's 4.75 ERA is below league average, his 13.6 strikeouts per nine rank 11th among relievers and he also ranks in the top 25 in lowest home run rate. Diekman's biggest bugaboo has been control, as he is walking nearly five batters per nine, in line with his career numbers.

With Diekman, Blake Treinen, Liam Hendriks and Lou Trivino, the A's are assembling one of the hardest-throwing bullpens in the major leagues, hoping to ride it to the postseason as they did last year.

Oakland's 3.94 bullpen ERA ranks seventh in the majors.

This is the second trade this month between Kansas City and Oakland. The A's acquired starter Homer Bailey for infielder Kevin Merrell on July 14.

Diekman signed a one-year, $2.25 million contract, which included a mutual option for 2020, with the Royals in the offseason. He has also pitched for the Phillies, Rangers and Diamondbacks and has a career 3.87 ERA.

Blanco, 26, who was signed as an international free agent in 2017, was batting .276 with 44 RBIs and 27 stolen bases for Double-A Midland this season. Aquino, 20, was 1-1 with a 4.58 ERA over 10 appearances in the Arizona League.

In a corresponding move, the Royals recalled right-hander Kyle Zimmer from Triple-A Omaha.