OAKLAND -- Esteury Ruiz was essentially on standby for most of Monday. He arrived to the A’s clubhouse earlier in the afternoon and partook in pregame workouts while the club mulled over whether to place J.D. Davis on the injured list.

About 20 minutes before first pitch, Davis landed on the IL and Ruiz was officially recalled from the Minors. Coming off the bench as a pinch-hitter in the eighth inning, he emphatically pronounced his return, swatting a Statcast-projected 406-foot solo shot for what went down as Oakland’s only run of the night in a 3-1 loss to the Cardinals at the Coliseum.

It could not have been a better first at-bat back for Ruiz given the circumstances of his demotion. When the A’s optioned him to Triple-A Las Vegas on April 1, general manager David Forst cited a need for Ruiz to improve his quality of contact.

In 2023, Ruiz ranked in the first percentile of Major League hitters in hard-hit rate (20 percent) and average exit velocity (82.7 mph), while his 2.5 percent barrel rate ranked in the fourth percentile.

“He’s got to cut down on strikeouts,” Forst said of Ruiz that day. “And when you put it in play, put it in play hard.”

His first swing in the Majors since that demotion certainly packed a punch. After taking a called strike from Cardinals left-hander JoJo Romero, Ruiz turned on an 0-1 changeup down in the zone and unloaded for a homer that landed halfway up the left-field bleachers. The exit velocity of 106.8 mph marked the hardest-hit home run of Ruiz’s Major League career and the fifth-hardest-hit ball of any kind.

“Great at-bat,” A’s manager Mark Kotsay said. “I’ve continued to follow him [in the Minors]. The swing is definitely looking better and more direct. The result was exactly what happens when you take a good swing on a ball in the middle. That’s a good sign.”

Having watched almost every single at-bat during Ruiz's 11-game stint at Triple-A, Kotsay noted that Ruiz had swung at over 70 percent of in-zone pitches he saw.

That’s a sign that Ruiz was identifying the correct pitches to attack, which to Kotsay was even more encouraging than the outfielder’s eye-catching overall numbers -- he hit .326 with three homers, eight RBIs and seven stolen bases in 11 games with Las Vegas.

“Now, it’s about putting the right swing on it,” Kotsay said. “He has power. He has the ability to hit the ball. We’ve seen exit velocities of 110 [mph] before, just not consistently. That’s really what we’re focusing on. Getting him on the barrel more consistent. There’s still some adjustments to be made, and he’s continuing to work on them.”

Ruiz has worked to adjust his mechanics at the plate by trying to stay back on his back leg and fixing his posture to be more direct to the ball and avoid swinging upwards.

Maintaining those changes are something he believes will lead to that more consistent hard contact the A’s are looking for from him, which, in turn, will ultimately help him get on base for more opportunities to utilize his elite 80-grade speed that helped him set an American League rookie record with 67 stolen bases last season.

“It helped me a lot,” Ruiz said in Spanish of his time at Triple-A. “I went down there to work on some adjustments I needed to make. Little by little, I’ve been seeing good results from those adjustments. It continues to get better. … I’m just trying to make good contact. If the homers come, I’ll gladly welcome it.”

Ruiz’s big swing was the lone highlight for a slumping A’s offense whose 48 runs on the season are second-fewest in the Majors. On a night that saw Ross Stripling turn in his best outing yet in an A’s uniform by holding St. Louis to three runs over 5 2/3 innings, the task was difficult against Cardinals starter Sonny Gray, who shut down his former team across six scoreless frames with six strikeouts.

“We knew it was going to be a tough night,” Kotsay said. “You don’t hand out $75 million to a pitcher and not get a guy that can do what he did tonight. We saw it last year from him. We knew he was tough. We took our at-bats and tried to grind him out, but we really couldn’t figure him out.”