"He called me into his office," Pinder said, "and told me I wasn't going to be helping them that night or the next day or in the playoffs, and I was like, 'What are you talking about?' and he told me, 'You're going to the big leagues.' It was an exciting moment."
And the promotion isn't considered temporary. The A's are moving full steam ahead with a youth movement that will carry them into the 2017 season, meaning Pinder, their second-round pick in 2013, will get a good look at the big league level as the season expires.
"You don't start the clock on somebody like this if you don't expect him to be here the rest of the year," A's manager Bob Melvin said.
Pinder, 24, will mostly platoon at second base with Max Muncy, taking over the role previously held by Tyler Ladendorf, who was placed on the disabled list on Wednesday with a sprained left wrist. Pinder will also see time at shortstop when Marcus Semien goes on the paternity list within the next week, and he also has experience at third base.
Pinder was batting .258 with 14 home runs and 51 RBIs in 107 games for Nashville.
"He swings the bat well, has got some power, and we saw that in spring," Melvin said. "It's great that he gets an opportunity.
"His offense is probably ahead of his defense, and he had some errors in Triple-A, but from what I'm being told, a lot of them were early and his defense has gotten better."
"There's been a lot of ups and downs," Pinder said, "but for the most part, it's been pretty positive, because even when I've been struggling, I've been learning about myself as a player."
Ladendorf, limited by his wrist in recent days, particularly when batting, was just 1-for-12 across 10 games in his most recent stint with the A's. Melvin said the injury is similar to what he endured last year, "and the numbers would suggest that."
The A's have used the DL 26 times this season, setting an Oakland record.