If the Cubs lead after 5 (or even 4 1/2) it's over. The new rule relates to the situation where the Cubs lead after the last completed inning, but the Cardinals take the lead in the top of an inning without the Cubs getting their at-bat that inning. Under the old rules the game would have reverted back to the last completed inning, the Cardinals' runs come off the board, and the Cubs win. Under the new rules the Cardinals keep their runs, but the game is suspended and resumed at that point.