Why 85 wins?
Right now, Fangraphs end of season projections have the Nationals getting the first wild-card at 88 wins, and the Brewers taking the second at 83 wins. 85 wins would be lower than normal in terms of the cut-off for the wild-card. Indeed, since the second wild-card came into play for the 2012 season, one 85-game winner has made the post-season: the 2017 Twins. But the National League this year is remarkably flat. Just the Braves and Dodgers currently have a W% that translates to 85 games over a full season: the Cubs, leading the NL Central, are on pace to win only 84.6. No team in the double wild-card era has won their division with fewer then 88 victories, but whoever wins the Central this year, probably will.
The schedule overview
Arizona has 71 games left to play. The good news is, 39 of those will be at home, compared to 32 away. Or maybe that’s not so good, considering the team has played rather better away from Chase Field so far: they are 26-23 on the road, compared to only 20-22 in Phoenix. But it should offer them at least a theoretical edge the rest of the way. They also are playing slightly weaker opposition. The average win percentage of their opponents for those remaining 71 games is .494; the Pythagorean win percentage, incidentally, comes in almost the same, five points lower at .489.
However, the D-backs have only 24 games to play against teams currently with winning records. They have 15 against teams exactly at .500 (the Padres and Cardinals), and 32 against teams with losing records. That includes three versus the Orioles, and a total of seven facing the woeful Marlins, which balances out the seven remaining against the Dodgers and two games in New York versus the Yankees. In particular, they face winning teams at Chase in only fourteen of the thirty-nine remaining games: the Dodgers and Brewers for four apiece, the Nationals and Phillies for three-game series.
Projecting the route
[Those with an aversion to math can skip the next paragraph and join me back again after it!]
This is using a similar technique to the one I used before the 2016 season. Basically, I’m taking our Pythagorean W% and comparing it to that of the opponents. The home team gets a .028 boost, and the road team a demerit of the same size (last year across the MLB, home teams had a W% .528 compared to .472 for road teams). The ratio of the two (D-backs W%/D-backs W% + Opponents W%) then gives us our chances of winning that particular game. For example, the series in St. Louis. The Cardinals W% is Pythag W% (.502) plus the home bonus (.028) = .530. Arizona’s is their Pythag W% (.555) minus the road demerit (.028) = .527. Our chance of winning each game is .527 / (.527 + .530) = .499.
Repeat for each of the 71 games remaining, add up all the odds and what do we get? By this method, the D-backs are projected to go 38-33, which would take them to 84 wins. Now, this is dependent on a lot of things. Most obviously, the team playing to their run differential going forward, which hasn’t happened so far - our poor one-run record is testament to that. It also depends on the run differential being maintained: our offense scoring at the same rate, and the pitching being as good at suppressing the opposition. None of this is at all guaranteed, and all it takes is one injury to a key player, for this to be entirely worthless. But it does show that 85 wins, thanks to the schedule, is by no means an impossible target.
They do need to do fractionally better than those expectations, however. For amusement, I pro-rated the wins onto a schedule which got us to exactly 85 wins after the final game of the season. Here are the points on the calendar at which the expected wins were close to a whole number, at the end of play that day: you can use this as a guide going forward, to see if the D-backs are ahead of, behind or on schedule for that 85-win total.
- First-half: 46-45
- Tue, July 16 @ Tex: 2-2 (48-47)
- Tue, July 23 vs. Bal: 6-5 (52-50)
- Wed, July 31 @ NY: 10-8 (56-53)
- Sat, Aug 17 vs. SF: 18-15 (64-60)
- Sun, Aug 25 @ Mil: 22-18 (68-63)
- Sun, Sep 1 vs. LA: 25-21 (71-66)
- Fri, Sep 13 vs. Cin: 31-26 (77-71)
- Sat, Sep 21 @ SD: 35-29 (81-74)
- Sun, Sep 29 vs. SD: 39-32 (85-77)
Should you prefer something simpler, if the D-backs go 4-3 over every seven games for the rest of the way, they’ll be at 86-75 going into the final game of the season. Naturally, there will be nothing like that level of consistency. There will be good weeks and bad: but the deeper we get, if we can maintain that overall level, e.g. 8-6 after fourteen, 12-9 after twenty-one, the better our chances will be of reaching the post-season.