When Wilin Rosario plays first base, are teams trying to take advantage of Rockies? - Nick Groke
Nick Groke argues that Wilin Rosario's inexperience at first base is getting exposed by other teams. The Rangers in particular pushed bunts at Rosario, who failed to turn them into outs. Also getting a lot of press was when he cut off CarGo's throw to the plate when the throw appeared on line. For what it's worth, in a small sample UZR thinks Rosario has been brutal out there as well.
Rosario can't play the field and his hitting has steadily regressed as well.