Triplett: Spencer Rattler has started ‘rolling’ in Saints camp, but preseason looms as ultimate test

St. Widge said
No doubt. And it may depend on the situation. For instance, it's possible that Haener would come in if Carr goes down mid-game but that they would start Rattler if he had a week to prepare. Or vice versa.

Isn't there a rule where a team can carry a third QB and it not count against the 53?