One thing that would definitely say is going against the US is USAAF doctrine and equipment. The raids on Clark Field et. al. were carried out by the Japanese flying in the altitude range of 20,000 to 25,000 feet. This has serious implications and problems for the US.

First, the standard AA guns the US had in the PI in 1941 were 3" pieces and incapable of firing on targets at that altitude. This means virtually all of the US air defense guns are worthless in this fight.

Second, USAAF (at least in the PI) doctrine was to put up standing partols on a air attack warning (say with the enemy an hour out or more) and then reinforce these when the target became clearer and the enemy attack got closer. However, the standard practice was to set the defending fighters at about 15,000 feet. This represents roughly the maximum useful altitude of most 1940 vintage Allison engined fighter aircraft like the P 40. It is also about as high as older models could reasonably manage like the P 35 and 36.
By flying another 5,000 + feet higher the Japanese gave themselves an advantage of not only position but also one of virtual invulnerability. Even the P 40 would take as much as 15 or more minutes to climb the additional 5,000 feet due to the poor altitude performance of the Allison. This means the Japanese bombers are going to go unintercepted in many cases and that their fighter escorts can pick and choose how they engage the Americans.