"Oscar, come here," he heard Triple-A Memphis manager Ron Warner shout as the team sat in the clubhouse during a rain delay.
"You're not playing today," Taveras was told, much to his disappointment.
"Why? Why not?" he asked.
"Because you're going to the big leagues," Warner told him.
Taveras' journey to that moment has been marked by hype and anticipation. Baseball's No. 2 prospect, tabbed as the Cardinals' best prospect since Albert Pujols, has finally arrived in St. Louis.
"What I'm supposed to do is downplay it," manager Mike Matheny said. "We bring a young guy up who's 21 years old, and that still blows me away he's only 21. I'd be lying to you to say I wasn't excited for him."
It will be tough to downplay what Taveras did in his second at-bat of his Major League debut Saturday afternoon. Taveras crushed his first career home run 418 feet over the right-field fence, a solo blast in the fifth inning for his first hit, to give the Cardinals their first run before they went on to win, 2-0, over the Giants.
"That would be the way you'd like to have it start," Matheny said. "You never know when you put so much on a guy, there's an awful lot expected out of him. To come out and do what he did, I think validates what kind of talent he is."
After signing with the Cardinals as a non-drafted free agent in 2008 from the Dominican Republic, Taveras made his professional debut at 17. All the left-handed hitter has done since is produce at the plate.
He hit .386 in Class A, .321 in Double-A, and in 95 games between last season and this season at Triple-A, he's hit .316. Taveras won batting titles in both 2011 (Midwest League) and 2012 (Texas League) and was named the Cardinals' Minor League Player of the Year and the Texas League Player of the Year in 2012.
"What makes him special is the fact that he's been able to do certain things for an extended period of time instead of just a flash for a year or one season," Matheny said. "Just a pure hitter, a guy that seems to find the barrel of the bat pretty often. You can't deny what the statistics have shown."
His arrival to the Majors has been more a matter of when than if, and with first baseman Matt Adams on the disabled list, his time finally came Friday night.
He was greeted by Cardinals faithful Saturday with a standing ovation in his first at-bat, in which he flied out. Following his home run, he was summoned out of the dugout for another. Taveras struck out swinging in his final at-bat, going 1-for-3.
"There's definitely a high level of anticipation and excitement," Cardinals general manager John Mozeliak said. "When you take the time and you invest heavily in the international market, you're looking to someday maybe get a return like this."
Taveras waited at Triple-A this season watching other outfielders get the call. Randal Grichuk went. So did Shane Robinson and Joey Butler. Taveras answered the questions.
"Everybody said, 'Man, when are you getting called up?'" Taveras said. "I said, 'I don't know, I'm doing my job here.'"
Those questions now will disappear, but the expectations set for him will not. The message from the Cardinals has been not to expect too much.
"It's something we fight with every guy that comes up here is don't buy into the hype," Matheny said. "Don't buy into the fact that you think it's automatically going to translate, whatever you've done before. You've got to work."
The outfielder arrived in St. Louis on a tear. In his last 10 games at Triple-A before his promotion Friday, Taveras had hit .462 with hits in all but one game, including two three-hit games and a four-hit game.
For Taveras, who will get a strong look while the Cardinals move to three American League ballparks for seven games with a designated hitter spot next week, the message has also been that he doesn't need to do it all.
"This is a good place for him to be, a place where there are so many established players that have had great careers already," Matheny said. "He doesn't need to come in and be the answer. He can just be a good part and put his piece in there."
His first call upon getting the promotion was to his mother, who had simple words for him: "Good luck."
His emotions were summed up simply, too.
"Awesome," Taveras said. "Happy."