Some wondered why and how Winston was able to to do, given that the Saints changed just before the start of the regular season Taysom Hill's designation from tight end to quarterback. The perception the Saints created was that Carr would be QB1, Hill would be QB2, and Winston would be the emergency third quarterback.
It has caused some to suggest the Saints violated the emergency quarterback rule by using Winston after Carr was injured but Hill was still available.
The truth is far less nefarious. The Saints haven't been using the emergency quarterback rule. Instead, they have been giving Carr, Hill, and Winston spots on the game-day active roster. Thus, Winston has been free to play at any time, regardless of whether Carr or Hill are playing.
This weekend, if Carr's shoulder injury keeps him from playing against the Buccaneers, it will be interesting to see whether newly-signed backup Jake Luton will be on the active roster, or whether he'll get the emergency-quarterback designation.
When that happens, the emergency quarterback appears on the inactive list, but he's noted as being the emergency quarterback. Again, the Saints had not used that device in any of their first three games. Carr, Hill, and Winston were free to play at any time, at any position.