The reeling Chicago White Sox have designated veteran shortstop Jimmy Rollins for assignment and promoted top prospect Tim Anderson from the minors.

The White Sox, having lost 12 of their past 15 games, announced the moves Friday before their game against the Kansas City Royals.

Rollins, 37, batted .221 with 2 home runs and 8 RBIs in 41 games with the White Sox this season. The three-time All-Star and 2007 National League MVP signed a one-year, $2 million deal with the White Sox prior to this season.

The moves are the latest in a busy week for the White Sox, who have traded for pitcher James Shields, signed veteran first baseman Justin Morneau and designated pitcher Mat Latos for assignment over the past six days.

Rollins got off to a solid start this season, batting .268 with six extra-base hits in his first 14 games. But he has struggled since then, batting just .194 since April 25.

Anderson, who turns 23 later this month, was batting .304 with 4 home runs, 20 RBIs and 11 stolen bases in 55 games at Triple-A Charlotte this season. He carried over that hot hitting into his debut Friday night, collecting two hits in the White Sox's 7-5 win over the Royals.

The news about Anderson was tempered somewhat by general manager Rick Hahn's announcement that center fielder Austin Jackson will likely miss at least six weeks because of a medial meniscus tear in his left knee and will have surgery next week. Hahn also said pitchers Jake Petricka (torn labrum in hip) and Daniel Webb (Tommy John elbow surgery) had season-ending operations on Friday.

With Jackson going on the 15-day disabled list, Chicago recalled outfielder Jason Coats from Triple-A Charlotte.

Hahn said that Jackson, who was recently sidelined by a turf toe injury, hurt his knee stepping on a base awkwardly during Thursday's win over Washington. He remained in the game, but an MRI on Friday confirmed the injury.

Asked if Jackson might miss the remainder of the year, Hahn said: "I don't think it's for the season, but until you go in there and see the extent of the repair that needs to be done, you don't know for sure. My expectation is it's a minimum of six weeks, but we'll see."

Jimmy Rollins batted just .221 in 41 games for the White Sox this season. Jim McIsaac/Getty Images

The 29-year-old Jackson is hitting .254 in 54 games after signing with the White Sox in March.

As for Anderson?

"Hopefully, it's very clear to everyone: He is not here to be sort of a savior," Hahn said about Anderson, who was rated as the No. 45 prospect in baseball by ESPN's Keith Law in March.

Hahn insisted this is simply the next step in the development of a young player who was sizzling in the minors. Even so, the expectations are hard to ignore.

In his major league debut, Anderson was batting ninth and starting at shortstop. He was also trying not to think "too much" about the expectations and hype surrounding him.

"Just go out and do my normal thing I've been doing, especially what it took me to get here," he said. "So just keep doing that."

Hahn and manager Robin Ventura said Anderson -- the 17th pick in the 2013 draft -- will be the regular shortstop, with Tyler Saladino serving as the backup.

Information from The Associated Press was used in this report.