Sullivan, 29, still had another two years remaining on his six-year, $25.6 million contract that included $10 million guaranteed. He had base salaries of $4.65 million coming his way in each of the next two years.
In 2014, Sullivan appeared in all 16 games for the Vikings and played a total of 997 snaps. Pro Football Focus has him rated as the No. 12 center of 41 qualifying players, due to a very solid rating as a run-blocker.