The Cardinals have not ruled out bringing John Lackey back on short rest, a move that is more likely to happen if the Cardinals are facing potential elimination in Game 4. Lackey did not throw a side session during Sunday's workout, nor was he actually at Wrigley Field. Without getting into any specifics, general manager John Mozeliak confirmed that Lackey was given permission to skip the workout.
When pitching every fifth day, Lackey typically throws his side session two days after his last start. Sunday would have been that day. But by not throwing, Lackey keeps himself an available starting option for Game 4.