NL Central could come down to head-on-head games among the three contenders.
The Cards and Pirates play each other 13 times in the second half. Cards and Reds play 10 times. Reds play Bucs 9. That's 32 games among the three teams. Cards 23 games against Pirates/Reds is almost 30 percent of Cards' remaining schedule (Pirates 22 games v. Cards/Reds similar percentage).
Otherwise, the Cards seem to have a slight advantage by virtue of more home games remaining. They have finished the West Coast and have played more of their road schedule.
Just on a glance, it seems that the Bucs may have the toughest schedule overall, more road games, four in DC, a series in Texas. Reds and Cards play in Atlanta. Reds with 11 game West Coast trip to end July. (Sorry, 10 game West Coast trip, can't count.)
Pirates and Reds each play many games with NL West. Cards have completed more of the NL West schedule. Pirates finish up with several games v. Cubs/Pads/Reds in September. Cards finish up with Rockies, Brewers, Nats, Cubs. Reds finish with six Pirate games, but also Brewers, Astros and Mets.