Because Sam said Héctor Alcázar gave him 3 months to find the treasure but he never mentioned how long ago it was. No matter how long earlier it happened, Héctor Alcázar was still dead in real life
Maybe a month earlier
I think a few weeks or so
About 15 years
Assuming the story takes place 3 months before Uncharted 4, then Alcázar had been dead for 3 months
What do you think?