Pressure and expectations really mess with baseball players, plus these 80-something win teams would have historically been eliminated by now. The Padres and Mariners are incredibly un-clutch this year. Seattle's young pitching seems to have run out of gas. The Rangers had those epic bullpen meltdowns when their bats went cold, they got lucky they had a big cushion and slumped early enough to have time to get over it. The Blue Jays had the injury bug and clubhouse issues. The Astros are a classic case of championship hangover.
The NL has all these young, flawed teams overachieving with little expectations...until the pressure ramped up in September and suddenly none of them can keep it together.