Before joining the Wild Things in July 2012, Rosa was with the Normal Cornbelters of the Frontier League. He accumulated nine runs on 31 hits, including three home runs and 14 RBI in 39 games.
Rosa was drafted by the Chicago Cubs in the 22nd round of the 2006 MLB June Amateur Draft. He split time in 2007 with the AZL Cubs (Rookie) of the Arizona League and the Boise Hawks (Class A) of the Northwest League. He joined the Peoria Chiefs (Class A) of the Midwest League for the 2008 season and part of 2009. He concluded the 2009 season with the Daytona Cubs (Class A) of the Florida State League. In 2010, Rosa joined the New Jersey Jackals, of the Independent Canadian American-Association, before returning to the Chiefs. His 2010 season concluded with a total 12 runs, six doubles, 13 RBI and a .161 batting average over 49 games played.