Well, I'll admit, you got me there.
So the Jews were super strategists blessed by God except when they weren't blessed by God. Stands to reason.
Of course the same thing could be said about just about any other group of humans who claimed that when things went well they were blessed by their god and when things went bad they were being punished by their god.
Of course that is precisely the standard "Why do bad things happen to good people" answer.
It is the most handy way of dealing with the famous "Problem of Evil". It's workable. But kind of makes you wonder how you can tell THIS group of blessed people who are currently being PUNISHED apart from the opposing group of "bad" people who are now mysteriously BLESSED such that they can defeat the people punished by their god.
This is why it is helpful to look at ALL the pieces on the game board, and not just your own.