AJ McCarron was brought in by the Houston Texans to be their back up quarterback, simply because this is a position they’ve not had since Deshaun Watson has been here. In his rookie season that he tore his ACL, Texans turned to Brandon Weeden, Taylor Heinicke, and current assistant coach T.J. Yates.
Last season, there was also not a reliable back-up option outside of an aging Weeden. Fortunately, the Texans didn’t need to turn to Weeden as Watson stayed healthy all season but it would not have necessarily been a great sign of assurance for Weeden to had play multiple weeks.