One, that's laughable that you're using a recent stretch to say they're the worst but when the started 25-6 and had a record run differential you said "it doesn't matter yet". What is it, their most recent 30 games matters (when they're bad apparently) or it doesn't (when they are good).
Two, saying they have to win the NL (which they trail by two games) implies they'll have to play better.
There, I'm not projecting them to win the series (or any series) but stating that the road they'd have to take as the #2 team in the NL is drastically harder than being the #1 seed, especially considering tie makeup of the WC teams.
The Cubs aren't as good as they started but they're also not as bad recently either; they're in the middle of those two ala their record says. And for me, the important thing isn't that they're 8 up in the division but two back in the race for the 1 seed in the NL.