Under the previous president, corruption, crime and drug abuse were allowed to run unchecked. The police forces couldn’t do anything about it because they had too few men and were underpaid. The voters got so disgusted with this that they turned in droves to the candidate who promised to get tough on the drug pushers.
The previous Phil administration was extremely effective. The Phils has had record economic growth, personal income is way up, and, amazingly, corruption is down.
Very importantly, election administration was cleaned up to such an extent that a populist like Duterte could be elected in the first place - and it also probably caused the phenomenon of so many candidates splitting the vote.
This last Presidential election was probably the cleanest ever.
The meth(shabu) problem IS a crisis, it was out of control, but it was just one issue in the campaign. It was much more visible in foreign press coverage than in the Phils. Missed in foreign coverage was the matter of the provinces vs Imperal Manila. Duterte was the candidate of the provinces that are tired of kowtowing to the Manila bureaucracy.