30 games in: The Arizona Diamondbacks’ playoff odds

Another ten games in the book, so time to revisit the standings, the playoff odds of the various projection systems, and what history tells us has happened to previous teams with the Diamondbacks’ current record.

The last 10 games

After a bright start, taking three of four from the Padres, the team lost back-to-back series, at home to the Rockies and on the road to the Nats, meaning they finished this stretch at an even 5-5 record. However, they outscores the opposition by a margin of 45-38, with only one defeat by more than two runs. Indeed, Arizona has one “blowout” (5+ runs) loss this year, the 7-1 defeat in the first game against the Dodgers, compared to six blowout wins. At the same point last year, we had already experienced five blowout losses, with only three such wins. This is a good sign: our season Pythagorean record, based on runs scored and allowed, is one game better, at 18-12.

The projection systems

• Baseball Prospectus: 36.1% (9.7% div, 26.4% wildcard)
• Fangraphs: 38.9% (7.2%, 31.7%)
• FiveThirtyEight: 39% (18%, 21%)

Something for everyone here, with one projection system up, one down and one unchanged! Prospectus drops out hopes a little: the divisional chances in particular take a knock, going down from 12.1%. However, this is somewhat balanced by an increase in wild-card odds, meaning the overall number is down 0.9%. Fangraphs goes strongly the other way, giving us a 12.0% boost, with both categories increasing. The 9-3 win over the Padres on Apr 25th seems to have had the biggest impact. Finally, there was no change over in the odds at FiveThirtyEight, though one percent was swapped from chances of winning the division to taking a wild-card.

Here’s the Fangraph graph of odds over time - I’ll use the one with all the NL West teams, which I think gives a little better perspective of how things have changed.

Across the National League as whole, I do feel it was a good week for the D-backs, as another leading pre-season candidate hits a severe problem. Before the season, USA Today had the Giants and Mets as the wild-card winners, both getting 89 wins. However, pitcher injuries and poor performance have taken their toll: Fangraphs now has both projected to win fewer games than the Diamondbacks, and the door appears to have opened for someone to step in. Right now, just five National League teams are above .500 and with a positive run differential: the Cubs and Nationals (who appear to be cantering away with their divisions), plus the D-backs, Dodgers and Brewers.

You’ll notice the absence of the NL West leading Rockies from the list. That’s because they have been outscored (albeit narrowly) so far. Their current record is massively based on a 9-0 record in one-run games. Now, while those wins aren’t going away, that is generally not regarded as a sustainable method for success. Though, I must say, it can work for a season, as the 2007 D-backs proved. They were outscored by 20 runs, but still had the best record in the NL, thanks to going 32-20 in one-run games. Inflicting some regression on Colorado this weekend would be very helpful.

Previous 30-game records

I’ve analyzed the results since 1998 of all 570 teams to this point, and whether or not they made the post-season. The chart below breaks down the records, and also lists the teams currently occupying each band in the 2017 standings. I used win percentage to decide their block, on an “at least” basis, e.g. you need at least a .600 W% to get into the 18-12 level.

This historical projections shows the D-backs down three percent, at 31.4%, based on previous performances of teams which have gone 17-13. However, that figure is likely a little low, since it’s slightly below the playoff percentage of teams which went 16-14, probably the result of random noise. Everywhere else though, we do see a steady decline from top to bottom. Things continue to look bleak for San Francisco and Toronto, and Kansas City have now joined them in the “serious long-shot” department.

Averaging out all four systems, we come up with a consensus value for the D-backs playoff chances of 36.4%, Despite only going 5-5 since last time, this is still up a couple of percent on the conssenus after 20 games, which was 34.3%. As long as this figure keeps trending in an upward direction, I’m content. After the Rockies series, the next section sees home stands against the Tigers and Pirates, and the start of a series against the Mets. With all of the last three having worse records than us, it’s a stretch of the schedule where we should look to seize the initiative. Taking this weekend’s series in Coors would be very useful.