At the outset of the War, MacArthur was the supreme Commander in the Philippines, not the US Army. He was immediately recalled. But the point is the he was caught off guard as well.
There are very few innocent parties in this part of the war.
FDR federalized the Philippine army in July of 1941 and recalled MacArthur to active duty naming him commander of the United States Army Forces in the Far East. War broke out Dec 7/8, 1941.
But the point is the he was caught off guard as well.
He wasn't caught off guard, he was busily preparing for war and US forces in the Philippines were on alert the morning of Dec 8, 1941. The Gods of war just happened to be favoring the Japanese that morning.