Hartsock signed with the Patriots on Monday.
Used primarily as a blocking tight end, the 34-year-old Hartsock has only 31 career receptions in 131 games. Football analytics website Pro Football Focus ranked Hartsock as the top run-blocking tight end in 2013.
This is the seventh transaction involving a tight end the Patriots have made since Sunday, ESPN's Mike Reiss points out.
- Dan Gartland