While Matheny rarely announces that someone is off limits for competitive reasons, it's hard to envision him calling upon Edward Mujica or Shelby Miller for the second game of the three-game series against the Cubs.
The concern with Mujica is workload-related. The right-hander, who admits he's feeling some fatigue, has appeared in six of the team's last eight games. He is one appearance away from matching his career high of 67.
Miller hasn't been burdened with a heavy workload, but his inexperience as a reliever factors into how Matheny uses him. Having ascended through the Cardinals' farm system exclusively as a starter, Miller has never pitched on consecutive days. In fact, none of his four Major League relief appearances have come with fewer than four days off.
Miller threw 13 pitches in an appearance on Friday.
"We're going to be careful with a young player like that who hasn't been exposed to back-to-back days," Matheny said. "It's getting accustomed to the whole routine of what a reliever does. There's a progression, typically."
The Cardinals' conundrum in the back end of their 'pen is the result of playing so many close games. Ten of the team's 19 games this month have been determined by one run. Only four of those contests have finished with a margin of victory greater than three.
As a result, Mujica, Boggs and Motte have already been called upon to make a combined 31 September appearances.
"That's not necessarily how we want it to line up, but we've been in a lot of close games," Matheny said. "Every one of them it seems like it's one play away, one pitch away from positive, negative. It shows the team is competing. We're right there. And when you're right there at the end of the season, you have to take your best shot."