In winning his fourth straight start, Griffin (14-9) struck out eight and walked just one batter.
Making his first start since being recalled from Triple-A, Minnesota's Scott Diamond (5-11) allowed five runs in 4 2-3 innings.
PIRATES 3, CUBS 1: In Pittsburgh, Jeff Locke allowed three hits over seven innings to earn his first victory in nearly two months.
Locke (10-5) struck out five and walked one to help the Pirates win their fourth straight as they try to catch first-place St. Louis in the NL Central. Mark Melancon worked out of a two-on, none-out jam in the ninth for his 14th save.
Jordy Mercer went 2 for 4 with an RBI double for Pittsburgh. Marlon Byrd and Pedro Alvarez each added an RBI single.
Chris Rusin (2-4) gave up two runs and four hits in seven innings for the Cubs.
NATIONALS 7, METS 2: In New York, Ryan Zimmerman, Adam LaRoche and Wilson Ramos homered off Aaron Harang in his Mets debut, and Washington completed a four-game sweep.
Anthony Rendon also connected for Washington, which outhomered the Mets 13-0 in a series that helped the Nationals remain on the fringe of the NL wild-card race.
The Mets have lost nine of 11 and fallen to 64-81, ensuring a non-winning record in all five seasons at Citi Field.