“They need someone who has a good core understanding of all those things … but who, most importantly, understands how to use the resources that are there in the agency already to their maximum effect,” said Jerilyn Perine, Donovan’s predecessor and a principal architect of the mayor’s original affordable housing plan. She said, for example, that the housing commissioner might focus more on code enforcement than housing development to ensure that the affordable units that currently exist do not fall into disrepair.