Carreras was added to the Rockies' 40-man roster Tuesday.
Carreras, who turns 23 in January, has impressive physical tools on both sides of the ball, but he struggled in a small sample at Double-A last season (80 wRC+, 30.9 percent strikeout rate in 19 games). He hit .289/.352/.473 with 11 home runs and 17 steals in 110 games at High-A.