This says it all right here. He had a ton of talent coming out of college. Years of torture behind the Texans line and Panthers line last year has led to a talented QB with low confidence and bad mechanics.
Sitting behind Brees and learning under SP will allow him to build his confidence and become a good backup QB that isn't one hit from a coffin or applying for his AARP card.
Everyone on this board knows that the Saints will go as far as Brees can take them and JM wasn't the answer if something was to happen to Brees. A rejuventated Carr could be serviceable if called on once he gets his mechanics fixed and his confidence back.
I say bring him in, it won't cost much. Another one of those low risk, high reward deals the FO likes to do.