Cubs are 8.5 up on Bucs and 10 up on the Redbirds, in the first week of June.
Is this real life?
Looking at the June schedules for each team, the Cubs might be able to widen that gap further.
Admittedly, this eye test method for strength of schedule isn't the best, but June looks to be favorable for the Cubs when compared to the Pirates and Cardinals.
-Cubs: Opened with 2 wins vs. LAD on 6/1 & 6/2 (2nd in division), 3 vs. AZ (4th), 3 @ PHI (4th), 3 @ ATL (5th), 3 @ WSH (1st), 3 vs. PIT (2nd), 3 vs. STL (3rd), 4 @ MIA (3rd), 3 @ CIN (5th), 1 @ NYM (2nd).
*9/28 games vs. 1st or 2nd place teams
-Pirates: Opened with 2 losses @ MIA on 6/1 & 6/2 (3rd), 3 vs. LAA (5th), 3 vs. NYM (2nd), 1 @ COL (3rd), 3 vs. STL (3rd), 3 @ NYM (3rd), 3 @ Cubs (1st), 4 vs. SF (1st), 4 vs. LAD (2nd), 2 @ SEA (Tied 1st)
*16/28 games vs. 1st or 2nd place teams.
-Cardinals: Opened with a loss @ MIL on 6/1 (4th), 3 vs. SF (1st), 3 @ CIN (5th), 3 @ PIT (2nd), 3 vs. HOU (4th), 3 vs. TX (Tied 1st), 3 @ Cubs (1st), 3 @ SEA (Tied 1st), 2 @ KC (1st), 2 vs. KC (1st)
*19/26 games vs. 1st or 2nd place teams.