Fact remains FDR left our military unprepared for a war that was obviously coming.
And except for a lot of lucky breaks, would have lost both the Pacific and European Theaters.
Actually, we were remarkably well prepared, considering the isolationist stance of the United States. War just came about 1 year too early.
The United States had already started the draft, had one of the largest navies in the World, and most of the aircraft and equipment we fought with in WW2 had either been put into production(the B-17) or had been designed and would be in production(P-51).
FDR dragged the United States rather unwillingly into preparing for WW2 at a time when the country was firmly isolationist.
There is no chance we would have lost in the Pacific- even if we had lost our carriers at Pearl or at Midway, our building program was already churning out ships and planes that the Japanese could not hope to keep up with.
And by 1945 we would have had the atomic bomb.
We didn't succeed because of lucky breaks- we won some key battles with some lucky breaks- but the war we won because of our troops and our industrial war production- led by FDR.