Cubs just need to go 8-8. There are 5 "non Cardinals/Brewers" games left on the schedule. Even if you win all 5 of them, that means the Cubs went 3-8 against the Cardinals and Brewers. Lets say its worst case scenario and all 3 wins are against the Brewers meaning the Cardinals won all 7 of the upcoming games. If that were to happen, the Cardinals would still need to go 4-4 in their other 8 games to win the division if the Cubs went 8-8 in their last 16. But again that's worst case scenario. A more likely slightly less disastrous scenario (for an 8-8 Cubs team) is the Cubs go 5-0 against Rays and Reds, go 2-5 against the Cardinals and 1-3 against the Brewers. If that were to happen, the Cardinals would have to go 7-2 in their other 9 games, and/or the Brewers 9-3 to overtake the Cubs. Also, the Cardinals and Brewers play a 3 game set the last weekend of the season, so that guarantees that 1 of those teams will lose at least 2 more games. Edit: And on the positive side, if the Cubs go 4-3 against the Cardinals and split against the Brewers, that would put them in a situation where even if they lost 3 of 5 reds/rays games, the Cardinals would have to go 9-0 and the Brewers 10-2 to overtake the Cubs.