CHICAGO -- Two veterans rejoined the Cardinals on Monday, though they'll have to wait another day to play. The club announced it activated infielder Jedd Gyorko and reliever Luke Gregerson from the disabled list prior to its scheduled series opener with the Cubs on Monday at Wrigley Field. The game was postponed shortly after due to inclement weather forecasts.
Reliever Mike Mayers and utility man Yairo Munoz were optioned to Triple-A Memphis in corresponding moves.
Gregerson's first appearance will mark his team debut, and it could come in his hometown. The Cardinals originally drafted Gregerson out of St. Xavier University in Chicago, where the righty also attended high school. He spent nine big league seasons elsewhere before returning to the Cards on a two-year deal this offseason.
Gregerson's debut will come after missing much of spring, and after a strained left hamstring required him to begin the season on the DL. His return, after four scoreless rehab appearances at Class A Palm Beach, gives the Cardinals three veteran options with experience closing games, alongside Bud Norris and Greg Holland.
Gyorko missed 12 games with a right hamstring strain suffered in his third game of the season, against Milwaukee. The infielder didn't appear in any official rehab games, opting instead to get at-bats in extended spring games on the backfields of the club's Jupiter, Fla., complex. He has been eligible to come off the DL since Friday.
Gyorko's return complicates an infield alignment Cards manager Mike Matheny entered the season expecting to shuffle regularly. First baseman Jose Martinez's white-hot start to the season probably means the bulk of Gyorko's playing time will come at second, at the expense of slumping Kolten Wong. But it can also help alleviate the workload of Matt Carpenter, who has played predominately third base in the early going.
Carpenter is hitting .160/.333/.320 through 15 games, while playing through lingering back and shoulder ailments. Wong is hitting .150 after beginning the year 0-for-13.
Righty Mayers earned a three-inning save Thursday in Cincinnati, the most notable of his three appearances. He was optioned for the second time in the season's first two weeks after making the club out of Spring Training.
The versatile Munoz, another rookie, was a sensation of spring. But his bat quieted in its first exposure to big league pitching. The 23-year-old hit .111/.200/.167 with 11 strikeouts in his first 20 career plate appearances.

Molina's Cooperstown comparison
The subject of Yadier Molina's potential Hall of Fame chances actually came up before Molina leapfrogged Johnny Bench on the all-time innings caught list Saturday.
"On the record, he is a Hall of Famer," Matheny said.
Nine innings later, after Molina had passed Bench for sole possession of 13th place with 14,493 1/3 career innings caught, the conversation continued.
Matheny said he grew up "idolizing" Bench, who won a record 10 Gold Gloves over a 17-year Hall of Famer career with the Reds. Molina can't match some of Bench's prodigious offensive numbers, but Matheny believes defensively the two are comparable. Molina is the owner of eight Gold Gloves.
"Yadi, doing anything that measures up to Johnny Bench, that would be the person I'm sure most people are saying is the greatest catcher of all time," Matheny said. "Yadi is, to me and to our generation, he's making that push to be that one guy who puts the accolades up there that people watch, putting himself in the conversation of one of the greatest catchers who ever lived."
Molina called it "an honor" to be compared with Bench, whom he's long respected. Bench congratulated Molina on the milestone on Twitter. More than anything, the innings caught numbers are indicative of durability.

"Most catchers, that's the thing you're shooting for more than anything else," Matheny said.
Even in his injury-shortened years, Molina has played at least 110 games in each of his 14 full seasons. He's averaged 1,079 innings caught per year, a rate that, if it holds, could move Molina near the top of the all-time innings caught list by the end of his career.
Molina, 35, plans to retire after his three-year contract concludes after the 2020 season. His workload could be altered as he ages into his upper-30s. But if he remains a full-time catcher, Molina has a chance to reach Jason Kendall, who ranks fourth on the all-time list with 17,478 innings caught. Ivan Rodriguez owns the all-time mark with 20,347 1/3.
Career innings caught, all-time

1. Rodriguez, 20,347 1/3
   
2. Carlton Fisk, 18,513 2/3
   
3. Bob Boone, 18,458 1/3
   
4. Kendall, 17,478
   
5. Gary Carter, 17,369
   
6. A.J. Pierzynski, 16,335 1/3
   
7. Tony Pena, 15,973
   
8. Benito Santiago, 15,925 1/3
   
9. Jim Sundberg, 15,898 2/3
   
10. Brad Ausmus, 15,840 2/3
    
11. Lance Parrish, 15,200 1/3
    
12. Ted Simmons, 15,092 1/3
    
13. Molina, 14,493 1/3
    
14. Bench, 14,489
    Gibson made debut 59 years ago
    In addition to being Jackie Robinson Day, Sunday also marks the 59th anniversary of Bob Gibson's MLB debut. Fans can access the club's new #CompleteGamer campaign on social media, launched to honor the Hall of Famer.
    "Bob Gibson is one of the greatest pitchers in baseball history and one of the fiercest competitors in any endeavor," said Cardinals president Bill DeWitt III. "Gibson not only had more complete games than any other pitcher in Cardinals' history, his tenacity, legendary competitiveness and unrivaled commitment to excellence are just some of the qualities that make him the ultimate 'gamer' -- the highest compliment any athlete can be paid."