Marmol will also be tasked with infield instruction, a responsibility he'll share alongside bench coach David Bell and Mueller. Improving the infield defense is among the Cardinals' priorities heading into next season.
Shildt has been named the quality control coach, a somewhat ambiguous role, but one that will allow Shildt to be in uniform and assist behind-the-scenes during games, particularly with video and scouting work. Shildt managed the Triple-A Memphis Redbirds from 2015-16 and has been a coach or manager within the organization since 2004.
"We looked at the strengths of both Ollie and Mike Shildt and thought they would both be good complements to what we already had," general manager John Mozeliak said. "In Ollie's case, he obviously brings experience on the infield instruction, but also as a young manager, he has a full complement of skills to add to our club. Mike Shildt from just a pure teaching standpoint felt like he would address some of the areas that we needed to.
"Plus both Shildt and Ollie do have an analytical and modern approach to some of their techniques, and we thought that could also work well for us moving forward."
The lone departure from the big league coaching staff is Derrick May, who was hastily promoted to assistant hitting coach just before the start of the 2016 season. Mozeliak confirmed that May will not be returning to the organization in another capacity.
The rest of manager Mike Matheny's coaching staff will remain static, including Bell returning as bench coach, John Mabry as hitting coach, Derek Lilliquist as pitching coach, Blaise Ilsley as bullpen coach, Chris Maloney as third-base coach and Jaime Pogue as the bullpen catcher.
In filling out Matheny's coaching staff, Mozeliak said he placed a priority on promoting from within the organization.
"I wanted to try to find a way to do this internally [so as] not having it where you end up having people who are career Minor Leaguing and feel like there is never an opportunity [to move up]," Mozeliak said. "Under Mike, we've been able to accomplish that."
Jenifer Langosch has covered the Cardinals for MLB.com since 2012, and previously covered the Pirates from 2007-11. Read her blog, follow her on Twitter, like her Facebook page and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.