IMO the only thing Lance has to prove is he has it inside his head to be a franchise QB. He came in very raw so there was no question he needed a redshirt year. But his talent upsides are certainly there.
I believe that Mac might have been their initial choice, but I think they saw the higher ceiling in Lance. With Jimmy G under contract, it made it easier to take Lance. As Ram fans, we all would love Lance to fail. But we all saw how given good coaching and time to develop how a QB can blossom into a top talent, The perfect example of this is Josh Allen. He came in with a strong arm but was wildly inconsistent. With Josh Allen, his inconsistencies were clearly due to his mechanics. But the biggest question was could he be a franchise QB between the ears.
Lance doesn't have Allen's arm strength, but there is no denying the talent you see in his film. To be honest I had hoped the Niners would take Jones. IMO Jones has a lower ceiling than Lance. He was more ready to play than Lance but I believed the scouting reports of his having a lower ceiling than Lance because it fit what I saw on film. Too many times I saw the same deer in the headlights look in Mac that we have seen in Murray. I don't see that in Lance. In Lance, I see his biggest problem as trusting what he sees. That will come with experience and good coaching. If Shanny tailors the offense to play to Lance's strengths he will be a hard QB to beat by 2023 or 2024.
Last year I said that Lance had the rudimentary foundation of being a pocket passer who can read the defenses, which would make him better than Murray. Lance is a QB who will make a secondary defend the entire field, and a true threat to run with 4.5 speed. The DL will have to contain him while they rush. The LBs will have to be mindful of a QB who is a legit dual threat which will test their ability to read and react. If the Niners roll out another strong run offense Lance could give them the balance they need. Mahomes is an example of a true dual threat QB, and though Mahomes has a much stronger arm, Lance is much faster.
The key for the 49er offense is how well their interior OL plays. They have had some major turnover there. How well they run between the tackles and pass protect against AD, Gaines and A'Shawn will be their test. This is why I think 2023 will be the real test for the Niners and show us how good or not their offense really is with Lance and that OL.