[1][failed verification] In addition to football, Sullivan achieved a 138–6 record as a heavyweight wrestler, winning the state championship as a sophomore, junior and senior.

Although his physical attributes were less than many in his position, he was rated as the fourth-best center in the draft, projected to be picked in the third or fourth round.

[4][5] The first four rounds passed with fellow centers Mike Pollak, Cody Wallace and Kory Lichtensteiger all selected ahead of Sullivan.

That year, he started every game as the Vikings and their new quarterback Brett Favre improved their offensive ranking to No.

The following year, he struggled with a calf injury and missed back-to-back games away to the New York Jets and at home to the Dallas Cowboys, with Ryan Cook and Jon Cooper respectively filling in.

He missed one more game in 2011, a Week 7 matchup against the Green Bay Packers in which Joe Berger took his place.

As a reward for his efforts, Sullivan was given a five-year, $25 million contract extension by the Vikings on December 17, 2011.

On March 5, 2019, the Rams declined the option on Sullivan's contract, making him an unrestricted free agent.