I think part of the issue is the Saints drafted Penning when we had a clear need at LT and really had no other options to start at LT at the time. And the Saints then installed him as the starting LT as a rookie which lead fans to believe that he must be ready to start.
He clearly wasn't and we the fans should have been more patient with him and other guys who take more time to develop, but the team didn't help by handing him the starting LT job as a rookie before he was ready and then doubling down on that and starting him in his 2nd year before he was ready. They really should have brought in a vet to start at LT or figured out that Peat could play LT before later last year.