I’ve thought for years, or at least as long as I’ve been thinking about minor league baseball, that it would stand to reason that the teams with the best winning percentage at the Major League level would be most likely to have AAA affiliates with strong winning percentages in the same season. It’s time to test that assumption
It seems obvious, right? If a Major League team can keep their best players healthy, and productive, that team will win more games and won’t rely on AAA caliber players, who can then help the AAA team win. Sandy Alderson alluded to this effect, the coupling of MLB and AAA winning, when asked explicitly how to make a winner in Buffalo, at the beginning of September, saying, “First of all, things haven’t been that competitive in New York City either. Part of the problem, in both cases, in New York City and in Buffalo, has been the lack of productivity in the player development system….”
There was also this Mike Harrington article demanding that the Mets put a winner in Buffalo next season or the Bisons sever their relationship with the Mets.
Does the data support the connection between winning the big leagues and AAA? Weakly, I’d say.

I plotted each MLB team’s winning percentage through the 2008 season on the x-axis and each team’s AAA affiliate’s winning percentage on the y-axis. It’s quick and dirty. I found a positive, but very weak relationship between the records of MLB teams and their top minor league affiliate. For example, of our 120 pairs of records, 33 times, both the MLB team and minor league team both had records above .500 and 35 times they both had records below .500, accounting for 68 of our 120 cases. So 56% of the time, in the last four seasons, when a AAA team has matched its MLB team above or below .500.
Surprised? I don’t think so.
Look no further than this year’s AAA Championship game. The Indians’ affiliate in Columbus from the International League between the Royals’ Omaha affiliate from the Pacific Coast League. As I write this, Cleveland sits at exactly .500, while the Royals, despite a heralded farm system, and young talent in the big leagues, are 17 games under .500.
Obviously, if a player is thriving in AAA, he will eventually get the call to the big leagues, sucking wins away from his AAA team and transferring them to the big leagues.
We might expect that the distribution of talent in the big leagues is less equal than that in AAA. There is some evidence for this. The standard deviation of MLB winning percentages is .070, while for AAA it is .059.
The basic point is that for the vast majority of Major League teams, lets say 25 out of 30, the goal all off-season long is to build a winner at the Major League level, and build a AAA team that can support that mission. Winning at AAA is at best a tertiary mission, but sometimes a happy by-product of winning in the big leagues.