After making his debut with the Rockies in September 2011, Rosario played in 117 games for the Rockies in 2012. In his rookie season, he led the Rockies with 28 home runs, coming just two home runs short from becoming only the fourth rookie catcher in the Expansion Era to hit 30 home runs.
A native of the Dominican Republic, the 23-year old spent five seasons in the minor leagues before being called up the Rockies during his sixth season. He finished the season with a .270 batting average and .312 on base percentage.
The Rockies finished as the National League West's worst team, 30 games behind the San Francisco Giants for first in the division. The 64-98 record was the most losses in franchise history by the Rockies and was also the lowest winning percentage.