Yeah, looks like we passed STL on April 4th at 48.4% to 44.1%. Cards got close a couple times following that, but after hitting 36.3% on May 27th their season was pretty much over as far as the computers were concerned. Looking at BRef, the last time they were over .500 this year was on April 2nd when they were 2-1, so their season has essentially been over from the beginning.
Even when the Brewers had bottomed out at 34-34 on June 14th, they were still at 46.8% to win the division.
Reds peaked at 36.8% on July 8th. Cubs hit 33.3% a few times - Aug 6, Aug 8, Sep 6 - but have seen their odds evaporate after going 3-10 over their last 13 while the Brewers went 10-4 over the same stretch.
Ultimately neither the Reds nor Cubs were able to maintain their hot streaks long enough to overcome the surrounding mediocrity. Outside of a 49 game stretch from late April to mid June where they went 20-29, the Brewers have played at a 67-37 clip the rest of the season.
The Cubs longest run was going 50-28 from 0609 until 0906, but they started the season ten under at 26-36 and have hit another rough patch recently with the aforementioned 3-10 rut they are in.
Reds were just too streaky in general. W3, L3, L3, L6, W5, W3, L4, W5, L4, W3, W12, L3, W3, W5, L6, W5, L6, W3, L3, L3, W3. That's 91 total games (59% of their schedule) where they were embroiled in some kind of streak or another, going 50-41 while streaking with that twelve gamer putting them over the top. In the 63 games (41% of their schedule) where they weren't streaking they've gone 29-34.