De La Rosa was 2-2 with a 2.51 ERA in five starts for Boston this season. He has also made 12 starts over two stints with Pawtucket.
Vazquez, 23, made his major league debut Wednesday night.
The 37-year-old Pierzynski hit .254 with four home runs and 31 RBIs in 72 this season. He signed an $8.25 million, one-year contract with the Red Sox as a free agent in December.