The St. Louis Cardinals activated infielder Jhonny Peralta from the 10-day disabled list prior to Friday's game against the San Francisco Giants.Rookie outfielder Magneuris Sierra was optioned to Double-A Springfield in a corresponding move.Peralta, who has been sidelined since April 17 with upper respiratory issues, batted just .120 with three singles in 25 at-bats this season. The 34-year-old fared significantly better in three games with Triple-A Memphis, hitting .364 with a double and two RBIs.Sierra, who made his major-league debut on May 7, has hit safely in all seven games with St. Louis this season. The 21-year-old is hitting .376 with eight runs scored.

Sierra, 19, is slashing .344/.389/.444 with three home runs and seven steals in 163 games since being demoted to rookie ball.

Sierra's first assignment to a full-season league was a bit of a disaster earlier this season, so the Cardinals sent him to the Appalachian League so that he could get back on track. Look for the toolsy center fielder to get another crack at Low-A to start 2016, and hopefully he will fare better in his age-20 season.

Sierra is hitting .195 with a home run and four steals in 174 plate appearances with Low-A Peoria.

Sierra turned 19 earlier this season, so it is not a major cause for concern that he is struggling out of the gate in his first full-season assignment. His approach is the big issue, as he is striking out at a 27.6 percent clip while walking just four percent of the time. The Cardinals will probably keep it slow and low with Sierra over the coming seasons, but he has the tools to be a five-category fantasy contributor when he reaches the big leagues.