The Cubs-Diamondbacks series could impact which team becomes a wild card team. If the season ended on 1 September, the Cubs would be the second NL wild card and the Diamondbacks would be tied with the Giants for the third NL wild card (2 games behind the Cubs). By the end of the season, that could change.
Let’s compare the bullpens of then Cubs and Diamondbacks.
After quickly acknowledging that for the entire season the Cubs bullpen was much better (1.1 WAA vs negative 3.5 WAA), let’s focus on only August. Because bullpens change, that focus will give a better comparison.