The third baseman said Wednesday the wrist strangely began bothering him earlier that afternoon.
Having Alvarez back was a big boost for the Pirates, who entered Friday on a six-game losing streak but still only three games behind St. Louis for the second National League Wild Card spot. Alvarez has thrived during the day this season, entering the opener hitting .301 in 41 day games.
The Pirates are hopeful three straight day games at Wrigley Field will help Alvarez snap out of his most recent slump, as he came into the series hitless over his last 13 at-bats.
Manager Clint Hurdle said he thinks Alvarez's streakiness is something many young power hitters face, mentioning Hall of Famer Mike Schmidt as one example. Hurdle said the the ability to overcome it is what separates great power hitters from average power hitters.
"If you play every day and you have power-hitting skills, you're going to put up numbers," Hurdle said. "But consistency, that can drive it to another level. And that's what everybody wants, including the hitter, as well as the team or the organization."