The Colts signed Castle to the practice squad Monday.
Analysis:The undrafted rookie out of Duke failed to make the Colts' 53-man roster but did enough to receive an invitation to the team's practice squad. He logged 18 carries for 88 yards across the Colts' three preseason games and would be a candidate for elevation to the active roster if one of Jonathan Taylor, Seth McGowan or DJ Giddens were to miss time.
