I think you have to be fair, first and foremost. JB played very well for us all of last season against some very good teams. He made a mistake, owned up to it, and did his time. It's GREAT that his backup filled in for him so well, but it's still JB's starting job which he EARNED.
If he comes in and consistently plays below what Blythe brought to the table over the first 2 games of 2018 (and you have to consider who we have played) then I respect any decision by the coaching staff at that point to ensure we put the very best product on the field. Upshot is that we have, at the very least, inflated our depth at that position.