Marecic was recruited to Army, Yale, and Stanford, eventually opting to attend Stanford. In his first three seasons with the Cardinal, Marecic was used primarily as a fullback, blocking for Toby Gerhart. He was an excellent blocking fullback, and seldom carried the ball. In his junior year Marecic was brought in as an inside linebacker in short yardage situations. In his senior season of 2010, Marecic's part time linebacker assignment became full time. He was the only player in the Football Bowl Subdivision to start on both offense (at fullback) and defense (at inside linebacker). In the fourth game of the season against Notre Dame, Marecic scored a pair of touchdowns within 13 seconds of one another, first as a fullback on a short dive play, then 13 seconds later making an interception from his inside linebacker position, running it back for a score. In doing so he became the first player to score touchdowns on both offense and defense in the same game since Eric Weddle in 2006.
On January 10, 2011, he was named the inaugural winner of the Paul Hornung Award as the most versatile player in college football.
On April 30, 2011 Marecic was selected in the 4th round by the Cleveland Browns with the 124th pick in the 2011 NFL Draft. He was projected to play at fullback rather than linebacker. The Browns were reportedly impressed with his work ethic and approach to the game.