Alvarez's shot, an opposite-field blast on a high fastball, came with two men on in the first, capping a four-run inning. Wandy Rodriguez and the Pirates gave most of those runs back in the bottom half, as Ruben Tejada hit a leadoff single and then Justin Turner and David Wright hit back-to-back homers before the Bucs even recorded an out.
That seemed like it spelled doom, even given the early four-run lead, but Rodriguez settled down, and the Pirates tacked on three more of their own in the second, as Josh Harrison smashed a two-run triple to the gap in right-center (about a mile from any of the Mets' outfielders) and Garrett Jones reached on an error by Turner that scored another run.
The Pirates scored another run in the fifth when Elvin Ramirez walked in a run to make it 8-3.
Jones helped the Pirates to some insurance in the ninth, though, with a two-run, opposite-field homer.
The Pirates are now up to 76 wins, the most they've had in a single season since 1999.