A possible road-map for the Arizona Diamondbacks to the post-season

When the history of the 2018 Diamondbacks’ season is written, it’s possible that we may look on Daniel Descalso’s eighth-inning home-run on Sunday as a turning point. Before it, Arizona was losing 3-2, on course to split a series with the cellar-dwelling Padres, have a losing road-trip against three sub-.500 teams, and drop out of first place in the NL West. But Descalso’s blast tied the game up, and apparently galvanized the team. A.J. Pollock followed in the ninth with another homer, which proved to be the deciding tally. Arizona then cruised past the Angels, while the Dodgers got swept at home by the Cardinals. As a result, this morning we awaken to a pleasant sight:

For the first day since May 16, Fangraphs says that Arizona has playoff odds that are higher than those of Los Angeles. It’s quite a turnaround, considering that barely a month ago, the Dodgers were 55.6% ahead of Arizona (on July 21, LA: 93.6%, AZ: 38.0%). Indeed, even on Sunday, the gap was more than 25% (LA: 79.2%, AZ: 53.5%). But Kenley Jansen’s return to the Los Angeles bullpen proved a decisive factor in all the wrong ways for the Dodgers, while Paul Goldschmidt, David Peralta and Clay Buchholz propelled the Diamondbacks to a sweep of the other LA team. And it’s not even our wild-card odds. By a margin of 43.4% to 35.2%, they now say we have a better shot at the division.

Last night’s results proved a tipping point for the Fangraphs’ projection system, with Paul DeJong’s ninth inning homer providing the flapping butterfly. The reason for this change is something Jack alluded to in a comment. The Dodgers are still projected by FG as being better than the D-backs the rest of the way, by a whopping 113 points of win percentage. But as the remainder of the schedule shrinks, that’s not sufficient for them to make up the 4.5 games they are currently behind. If both teams win out at their Pythagorean W% (LA: .588, AZ: .573), the Dodgers would finish the year 87-75, the D-backs at 91-71. Colorado (W%: .488) would be tied with LA, and Arizona takes the division by four games.

Yes, there is now a very real prospect that the Diamondbacks can take their first division title since 2011. It’s far from certain, of course, but our fate rests entirely in our own hands. Of the 35 games remaining, 40% are the key contests against the Dodgers and Rockies, with the D-backs facing each three times at Chase and four on the road. While Colorado are closer to us than Los Angeles, I’m still not entirely convinced of their credentials. They remain outscored by their opponents this season, and if they stop winning those one-run games, they are probably toast [given their bullpen’s struggles, it’s odd they are 21-13 in those contests. I guess they are good at turning three-run leads into one-run ones!]

But their presence does still complicate the picture significantly. If it was a two-team race, I would be posting a nice chart about now. Results against the Dodgers across the top, results by the Dodgers down the side, and each cell showing what the Diamondbacks need to do to come out on top. However, with the Rockies also involved, the spreadsheet needs to be some kind of tesseract, and my ten-year-old computer [Windows XP for the win!] is likely not capable of handling the trans-dimensional math required. But we can still take a look at the remaining schedule and see what we find. First, let’s see if we can figure out the likely cut-off point for a) division victory, and b) a wild-card spot.

Looking at the 120 division winners since the D-backs entered the league in 1998, we’ve seen between 82 wins (2005 Padres) and 116 (2001 Mariners) be enough to give you the division. 100 wins makes you a virtual lock to take the title: I say “virtual” because in 2001, Oakland won 102 times, and still finished 14 games back of Seattle. [Both sides then lost to New York in the playoffs, for which, we thank them...] The break-even point appears to be 92 wins: 8 of 14 teams there won their division, a 57.1% rate which drops to 37.5% (3 of 8) at the 91-win level. However, the competitive NL West likely lowers the bar. The D-backs are currently on pace for 90.6 wins, so let’s put the finish line for the title at 91 victories.

For the wild-card, we only have six years worth of data under the dual wild-card system, introduced for the 2012 season. Looking at the 12 second wild-cards in each league over that time, they won an average of 89.2 games. The 12 third-placed teams in each league during the same time - the best team not to make the post-season - won an average of 85.8 games. Last year, 87 would have been enough to get you a wild-card spot in both the American and National Leagues. However, this season, the Mariners are on pace for 91 wins and the Phillies for 87: both would be playing golf if the season ended today. We’ll say 88 wins would be needed for an NL wild-card spot.

With 35 games left, the Diamondbacks therefore need 17 wins for a wild-card spot and 20 for the division, with the latter obviously the preferred option. To that end, here’s their remaining schedule, with in parenthesis a potential number of victories for Arizona in each series. By happy coincidence, the total number of wins by the D-backs over these 11 series adds up to... exactly the 20 victories needed for the division. What are the odds?

• 3 vs. Mariners (2 wins)
• 3 @ Giants (2)
• 4 @ Dodgers (2)
• 2 vs. Padres (2)
• 4 vs. Braves (2)
• 4 @ Rockies (2)
• 3 @ Astros (1)
• 3 vs. Cubs (1)
• 3 vs. Rockies (2)
• 3 vs. Dodgers (2)
• 3 @ Padres (2)

Breaking down the schedule this way, it seems eminently achievable. As ever, the key to success is to keep winning series. The above does include two series defeats across the 11 remaining, although all three of the four-game sets are a split, and the only sweep required is a two-game series at home vs. the Padres, likely among the easiest possible. Though quite how achievable these are on an individual basis is hard to assess. For instance. taking two of three from LA in the penultimate series will depend significantly on whether or not a) we face Clayton Kershaw, and b) the Dodgers have anything left to play for. If they’re out of the race, their motivation will be reduced to that of playing spoiler.

This schedule sees us taking four of seven from both the Rockies and Dodgers. Worth noting: they also have six games against each other. Ideally, they can cut each others’ throats and split those evenly. That scenario would give them each six wins over thirteen games. To match the D-backs’ theoretical 91 wins, the Rockies would then need to go 16-7 in their other contests and the Dodgers 18-3. That’s tough for Colorado and virtually impossible for Los Angeles. But, the important thing and the best idea, is for Arizona to keep winning their own games, and render what anyone else does, irrelevant.