I'm finding December 8, 1941 MacArthur's Pearl Harbor by William Bartsch very illuminating reading, his Doomed from the Start is next on my list.
The rapid fall of the Philippines, the nearly immediate destruction of the FEAF and the deaths and surrender of over 100,000 US servicemembers and Philippine soldiers is a classic case of too little, too late. The decision to reinforce and not quickly abandon the PI came far too late to organize, equip and train the defending forces. It wasn't until October 1941 that Marshall, Arnold (and Roosevelt) decided to massively beef up the offensive and defensive air capability. The decision to base 170 B-17 and B24 heavy bombers, 86 light and medium bombers and 195 first rate fighters in the PI by October 1942 was intended to deter Japanese aggression, particularly by threatening to bomb Formosa and southern Japan. Most of these aircraft were expected to be delivered by March 1942, with large quantities scheduled to arrive by the end of December 1941. Even though it was possible to achieve the aircraft totals in these timeframes, there were great obstacles in the way of having this formidable air armada becoming effective.
In December 1941, there were only two airfields capable of accommodating heavy bombers, Clark and Del Monte, and Del Monte was only a primitive 2600' strip. MacArthur and his Air Commanders initiated a crash airfield construction program, but there was too little time and too few resources and construction personnel to make the fields ready before the new bombers and fighters were due to arrive. A half dozen or so smaller fighter fields were still being improved or were under construction when the Japanese attacked. The lack of adequate airfields hindered the shipment of new aircraft and caused great congestion at the existing fields.
Maintenance facilities were either inadequate or nonexistent, particularly when only the heavies were planned to be ferried cross-Pacific intact. All other aircraft were to arrive by sea and needed to be assembled and tested before becoming operational. There were no spares for anything and no facilities capable for major engine overhauls. Brereton cabled Arnold a request for engines and spares with engines needing major repairs or scheduled rebuilds to be shipped back to continental US repair depots by sea. Prestone coolant was late in arriving with initial P-40 deliveries. There wasn't specific mention of an inadequate number of mechanics, but this is implied when an overall shortage of base support organization and facilities was noted.
Many of the newly arrived pilots and flight crew had come straight from flight schools, lacking any operational experience, no experience with the specific aircraft they were going to be flying and some with no multi-engine training when they were going to be flying bombers. There was an almost universal lack of gunnery training, and with a severe shortage of .50 caliber ammunition, only 2 of all P-40Es in country had been test fired. To gain/maintain gunnery skills, pilots trained with the .30 guns in older P-35 and P-26 pursuit fighters. There was also a bomb shortage.
Other roadblocks to a successful defense organization were personality conflicts and professional rivalries among several mid and senior level commanders holding key positions. The lethargic "tropical" 1/2 day work schedule and laid back attitude permitted by MacArthur persisted until the arrival of the sickly BG Henry Clagett in May 41, and it wasn't until the arrival of MG Brereton to assume command of the newly designated Far East Air Force in November that the air arm of USAFE began to take the imminent threat of war with Japan seriously, but by then it was too late to do much.
The depressing situation was similar with the U.S. led ground forces, and it all couldn't be laid at MacArthur's feet.