They were backups. But their situations are a bit different in that each received starters reps in practice once a week throughout the season (in place of Whitworth and Sullivan)- just like Blythe did in 2017. That is valuable work. And both were their game day backup OL all year. That in itself displays a degree of confidence in them. They were not the 8th and 9th OL in street clothes. They were active, playing special teams, and each a play away from playing.
So they have a lot of developing to do- especially in the next 6 months. But they aren't starting from scratch.