The Arizona Diamondbacks have swept everything before them this spring, losing just one of their last 15 games - there were only three such streaks during all of 2015 in the majors. Now, we all know a firm tenet of sabermetrics, is that spring figures have no correlation with regular season ones. But there has been some analysis lately suggesting that "if a team is very successful during spring training, there are examples that tell us they might be more likely to be a good team."
To dig into that, I scanned the spring standings back to 2003 [the earliest year for which I could find data], and pulled out the teams with a win percentage of .650 or better, discounting ties - to reach that point this season, Arizona need go 4-6 the rest of the way (or 5-7, if we count the two games at Chase). I then took those teams and saw what their records were in the regular season. Unsurprisingly, results were all over the place. Last year alone, the best record was a tie between the Oakland Athletics, who put up the worst showing among spring winners over the time studied at 68-94, and the Kansas City Royals, who merely won the World Series.
The correlation between spring record and regular season record was, indeed, very near zero: 0.038. However, the regular season mark for these teams wasn't 81-81 as you'd expect if results were truly random. On average, these 27 teams went 85-77. Perhaps more significantly, 11 of these top spring teams also won their division that year: a 41% rate, more than double the 20% you'd expect by chance. But if you narrow it down to the really good sides - those with a .705 preseason W% or better - while the sample size shrinks to half a dozen, four of those six won their division, and overall, they averaged 90.5 wins.
Again, I want to stress, it's not certain: the two sides with the best records of all, the 2013 Royals and 2012 Blue Jays, both missed out. But I'm curious to see what the protracted run of success this month has done, when we run the confidence poll at the start of April. Here is the data for the 27 teams, with their spring and regular season records and win percentages. The ones who ended up winning their division in bold and italics, so they stand out a bit.