You need to ask why? We saw why-- Injuries happen.
I did not say tell Devers he was next year's 1Bman. I said start with "Do some working out at 1B."
In 2022, we figured Dalbec was the 1Bman, but were not 100% sure he was "the guy." That was the Franchy at 1B year. (We also added Hosmer later in the season.)
In 2023, we had Casas and Turner, but maybe we don't sign Turner or use him at DH only.
In 2024, Casas looked like the FT'er, but to borrow your phrase, he was still rather "suspect." Dom Smith ended up starting more than Casas, and that was after we cycled through Dalbec and Garrett Cooper, first.
We all saw what happened in 2025- no refresher needed.