In our reality, the presidencies of Magsaysay, Marcos, and Aquino have helped solidify the role of the Philippines as second only to Japan in the Asia-Pacific Region. Following the end of Second World War, free-market policies and rapid industrialization helped the Philippines maintain its spot as Southeast Asia's largest economy and premier military power.
After Sabah voted to join the Philippines due to their prosperity and promise of religious freedom, the 'Sandata' nuclear test of the 60s, their uncontested control over the Benham Rise and the Spratly Islands, and the successful Philippine-led ASC (Asian Security Confederation) intervention into Greater Indonesia, which saw the independence of Malaya, Brunei-Sarawak, Singapore, Aceh, and other minor states, the Philippines was only second to none in Southeast Asia
What if, after the Second World War, the administration of the country wasn't as great as it was in our timeline?