CHICAGO—A little after 3:30 p.m. on Monday, Tim Federowicz sat at his stall in Wrigley Field’s home clubhouse, scrolling through his phone. He had a few minutes to spare before a 3:45 team meeting at the batting cage under a warm September sun, during which manager Joe Maddon would remind his Cubs to use the remainder of the regular season to work on shortcomings and burnish any rough edges before a potentially historic playoff run. Attendance was compulsory for anyone with a nameplate above his locker. That included the reserve catcher with 27 plate appearances all year—a guy who hadn’t taken a swing in a major league game since June 12.