My old DC friend Robert George notes that Yankees recent era of dominance started when a Democrat (Bill Clinton) was elected to the White House.
Of course, the two times the Mets won the World Series, a Republican was in the White House.
One other point. The 1970 UK General Election was something of a shock win for the Tories. The preference polls mostly showed it close, but with Labour winning. But polls asking who people THOUGHT would win were heavily Labour winning.
It was a shock but shouldn't have been -- though Labour started with a large lead, the Tories gained steadily through the campaign. In the end, the Tories won by a few percentage points, but comfortably in seats.
The reasons given usually deal with a mistimed late budget released by Labour with a little bit of Shy Tory factor (like Bradley factor, except that people did not want to admit being a Tory because it was uncool). Another factor was that Enoch Powell's anti-immigrant speeches may have thrown some traditional Labour voters to the Conservatives.
So where am I going with all this? There is another theory. Shortly before the 1970 General Election, on top of everything else, the English soccer team (who were defending World Cup champs) were knocked out by West Germany in spectacular fashion days before the election. Some commentators feel that with all the other bad news at the time, that was the final straw that killed Labour's chances.
Let's Go Mets!