Barring an epic collapse, the rule of thumb is that a team can realistically make up one game per week in the standings.
There are approximately 5 weeks left to go in the season.
The Brewers are 3.5 games behind the Cubs. The Cardinals are 4.5 games behind.
The NL Central rivals may be looking more toward a tightening wild card race than a division win.
But the Cubs still have 7 games left with each of the Brewers and Cardinals. That means that the Brewers and Cardinals are not out of the race even if they trail by 7 games before meeting the Cubs.
Another rule of thumb is that a team needs to take care of business in its own division. The only two teams left with an above .500 record are the Brewers and Cardinals. The Cubs still need to play well against division teams in order to avoid a bitter September surprise.