The Cubs started the season 2-7. They have been 23-7 since. The offense has done the job, but the biggest difference has been the pitching. When they started 2-7 on a nine-game road trip, the team ERA was a league-worst 7.51. Then they arrived at Wrigley Field for their home opener. And everything changed.
From April 8 (the home opener) on, the Cubs have a team ERA of 2.29. Best in the Majors by nearly a full run (the Rays are next with 3.22). The starting pitching has a 2.32 ERA – best in the Majors; the next best is the Rays at 2.