3 things Oliver Marmol has done well this year and 1 thing he butchered

Oliver Marmol butchered Jordan Walker's usage upon his recall.

A manager can't decide who is on the 26-man roster, but he can decide how to use them.

For the bulk of the season, former top prospect Jordan Walker was at Triple-A Memphis figuring out his swing. He needed to lift the ball more and drive it with authority, and the front office (rightly) placed him with the Redbirds to make the appropriate adjustments.

However, Walker was recalled in early August following an injury to Matt Carpenter. John Mozeliak wanted Walker to play every day to continue the progress he had shown in Memphis prior to his recall. Marmol, on the other hand, opted to play veteran and recently acquired outfielder Tommy Pham daily. Both players hit right-handed, and the team needed help against left-handed pitchers. This decision to play a veteran who was struggling over a young player who was showing signs of improvement is one of Marmol's worst this year.

This decision to sit Walker was Marmol's entirely, and it fell flat on its face. Walker was demoted once again just a week later, and he contributed very little during his brief stint with the major league squad. He has since been with the team throughout September, and Walker's output has been greatly improved thanks to regular playing time.

While Marmol has handled the roster well throughout the year, this blip on his resume is glaring. Walker's progress was stinted, and the up-and-down that he was put through during this time period did him no good. Had Marmol opted to play Walker more frequently in early August, the month could have gone much differently for the team.