CINCINNATI -- Randal Grichuk, who opened the season as the Cardinals' starting center fielder, headed back down to Triple-A Memphis for the second time this season as part of a series of roster moves the Cards made ahead of Tuesday's 7-5 loss to the Reds.
Left-hander Dean Kiekhefer was also optioned to Memphis along with Grichuk, who has struck out 22 times in 42 at-bats since the All-Star break. The moves were necessary as the Cardinals activated outfielder/first baseman Brandon Moss and infielder Jhonny Peralta from the disabled list. The club also added newly acquired reliever Zach Duke to the roster and placed Aledmys Díaz (right thumb fracture) on the DL.
Moss and Peralta immediately made their presence felt, with Moss going 3-for-5 -- including a game-tying home run in the eighth -- while Peralta contributed an RBI double in three at-bats.

The decision to option Grichuk left St. Louis with an eight-man bullpen -- before lefty Tyler Lyons was placed on the DL with a stress reaction in his right knee -- at least until the club is ready to pull Matt Carpenter (right oblique strain) off the DL later this week. Right-hander Jerome Williams remains that extra reliever and is an option to pitch in long relief, if the club has that need.
"Right now, just given coming off that 17-game stretch, coming off the multiple doubleheaders, coming off the 16-inning game, all of that puts a lot of wear and tear on the bullpen," general manager John Mozeliak said. "So from a comfort level, we thought it would make more sense to keep the extra arm."
Williams' presence also frees up Matt Bowman to be used in higher-leverage spots.

Grichuk was first sent to the Minors on June 18, and he stayed there until July 5. He got off to a strong start upon returning to the big league club and went 9-for-22 in the week leading up to the All-Star break. That positive momentum has since fizzled. So, too, had regular playing time, something the Cardinals want Grichuk to get in Memphis.
"For him, he's still trying to figure out who he is," Mozeliak said. "It's always hard to do that when you're having struggles at the Major League level. I think for us, we still believe there is a lot of talent there, and the fact that playing every day -- whether it's here or at Memphis -- should help him."
Kiekhefer rejoined the Cardinals one week ago and made three scoreless appearances during his stay. The Cards' need for the rookie left-hander dissolved upon the addition of Duke, who will take Kiekhefer's place as the third southpaw in the 'pen.
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Moss played in three games as part of his rehab assignment with Double-A Springfield and went hitless in eight at-bats. He missed nearly a month recovering from a left ankle sprain sustained at first base. The Cardinals will continue to utilize Moss as both a first baseman and corner outfielder.
Instead of rejoining St. Louis as a third baseman, Peralta comes back ready to be the team's everyday shortstop. Those plans changed on Monday after the organization learned that Diaz would be out for multiple weeks with a hairline fracture in his right thumb.
Peralta, who has been limited to 30 games this season because of issues with his left thumb, took three at-bats during a one-day rehab assignment with the club's Class A Advanced Palm Beach team on Sunday. He spent the minimum 15 days on the DL.