The constabulary werent considered high performing troops.
They were not committed to the MLR in Bataan but to beach defense.
The Philippine Division was used mainly as a counterattack force and to hold critical sectors.
But the bulk of the MLR, and most of the counterattacking, was by the Philippine Army. They had gotten much better through the course of the campaign, unforunately as they had deteriorated physically. Being in action is good training.
As it turned out beach defense was important . The Points and Pockets showed that. Though Gen King mostly assigned Constabulary and shipless bluejackets and planeless AirCorps to beach defense. They were successful. First read if the siege oh 60 years ago in John Toland’s But Not in Shame.