Patrick Saunders discusses the idea of turning Wilin Rosario into a full-time first baseman:

The idea seems plausible enough. Convert power-hitting catcher Wilin Rosario into the Rockies’ full-time first baseman of the future. Freed from the physical and mental burdens of life behind the plate, Rosario could become an even more potent offensive force.

The Rockies seem to me more interested in using Rosario as a part-time first baseman to keep his bat in the lineup when he’s not catching. The biggest reason against making Wilin a full time is his OBP. While his slugging percentage is over .500, his OBP sits just above .300. He did not have a high OBP in the minors, so there’s no reason to believe he’s going to develop one in the majors. First basemen should be complete offensive players. Talk of moving Buster Posey or Joe Mauer makes more sense since they are multi-dimensional hitters. Rosario is a catcher who has an offensive strength. The Rockies are probably better using him once in a while at first, and trying to develop or acquire a great hitting first baseman.