End of August update:
Since the last post, the Cubs have gone 9-3 against the Royals, Tigers, Pirates and Brewers, which would be successfully a "good run of wins to get in a solid position".
NL Contenders' records since August 19:
Dodgers 9-2
Brewers 8-2
Cubs 9-3
Braves 8-3
Phillies 8-3
Dbacks 7-4
Giants 5-6
Reds 5-7
Marlins 2-8
So...separation has begun to happen. Braves and Dodgers still 10 games clear of anyone else and have the byes effectively locked up unless someone else effectively goes undefeated in September. Brewers have played out of their minds and have gained just a half game on the Cubs in 2 weeks (thanks to the last 2 days). Phillies and Cubs have bought 2 games on the rest, while the Giants, Dbacks and Reds are within a game of each other for the last playoff spot, and the Marlins have slid to 3 back of the playoffs and 5 back of the Cubs.